new messenger opens links in EDGE instead of default browser.

Can we please stop making comments that are just complaints against Meta and Microsoft? Let's keep the discussion practical, centered around the solutions/workarounds.

NO.
We are complaining because the complaint IS against Meta and Microsoft. The only way to get a practical ACTUAL solution is to complain about the root problem.
. . .
So, please, stop making comments shilling for Microsoft and Meta, and show some respect and support for those who aren't interested in tacit support of these monopolies.

No shilling from me - I'm not happy with Meta and Microsoft either (although I do think the lion's share of the blame lies with Meta - it's their messaging service, and they are the ones who developed a non-browser app and then lazily abandoned it for a browser version; they are also the ones who didn't bother supporting Firefox for video/audio calling in the browser). But complaining on a user forum has no effect other than filling our email inboxes with notifications of more people complaining. When posted here, it's just venting, not lodging real complaints. Complaints should be sent directly to Meta (and Microsoft if you want to go that direction). I don't know if any Microsoft employees even look at this forum, but obviously Meta employees don't, so it's the wrong channel.

I don't know if Meta has a feature-request/feedback area, but https://www.facebook.com/help/messenger-app/ might be a place to start - if lots of people write help questions about how to get a non-browser-based app for Windows again, it might get their attention. The Edge relationship isn't the only problem with the new app - it also doesn't start automatically at bootup and doesn't notify the user of new messages/calls when not open, both of which the old app does quite nicely (it has a memory-resident piece that runs quietly in the background to detect new content and respond accordingly).

Can we please stop making comments that are just complaints against Meta and Microsoft? Let's keep the discussion practical, centered around the solutions/workarounds.

NO.
We are complaining because the complaint IS against Meta and Microsoft. The only way to get a practical ACTUAL solution is to complain about the root problem.
. . .
So, please, stop making comments shilling for Microsoft and Meta, and show some respect and support for those who aren't interested in tacit support of these monopolies.

No shilling from me - I'm not happy with Meta and Microsoft either (although I do think the lion's share of the blame lies with Meta - it's their messaging service, and they are the ones who developed a non-browser app and then lazily abandoned it for a browser version; they are also the ones who didn't bother supporting Firefox for video/audio calling in the browser). But complaining on a user forum has no effect other than filling our email inboxes with notifications of more people complaining. When posted here, it's just venting, not lodging real complaints. Complaints should be sent directly to Meta (and Microsoft if you want to go that direction). I don't know if any Microsoft employees even look at this forum, but obviously Meta employees don't, so it's the wrong channel.

I don't know if Meta has a feature-request/feedback area, but https://www.facebook.com/help/messenger-app/ might be a place to start - if lots of people write help questions about how to get a non-browser-based app for Windows again, it might get their attention. The Edge relationship isn't the only problem with the new app - it also doesn't start automatically at bootup and doesn't notify the user of new messages/calls when not open, both of which the old app does quite nicely (it has a memory-resident piece that runs quietly in the background to detect new content and respond accordingly).

They do not have feedback there; a workaround is that if you poke around in the help topics, and vote no on the "did this help you", you get a 500 character box to explain why it didn't help. I submitted some feedback that way. I hate these big corporations/brands removing all easy ways to reach them.

At this point my problem with using it as a web app or just having messenger.com open is that there's no indication of new messages, either on the tab or the taskbar. It's really annoying.

It's true that you won't get anything on the taskbar or toast notification with only a browser-based app or browser tab, because browsers don't connect to that Windows native functionality. The old app does give me toast notifications, and if a video/audio call comes in, it will display a popup where I can click to answer it, even if the app was not "open" at the time (it has a memory-resident component that monitors the communications). That's exactly what I want it to do.

But if I leave a tab open in Firefox with messenger.com in it (and it is not the active tab/window), I do get a sound when a new message comes in, and the tab title will usually (curiously, not always) alternate between the name of the conversation that is currently selected and the name of the conversation where the unread message is. Do you not get a sound?

At this point my problem with using it as a web app or just having messenger.com open is that there's no indication of new messages, either on the tab or the taskbar. It's really annoying.

It's true that you won't get anything on the taskbar or toast notification with only a browser-based app or browser tab, because browsers don't connect to that Windows native functionality. The old app does give me toast notifications, and if a video/audio call comes in, it will display a popup where I can click to answer it, even if the app was not "open" at the time (it has a memory-resident component that monitors the communications). That's exactly what I want it to do.

But if I leave a tab open in Firefox with messenger.com in it (and it is not the active tab/window), I do get a sound when a new message comes in, and the tab title will usually (curiously, not always) alternate between the name of the conversation that is currently selected and the name of the conversation where the unread message is. Do you not get a sound?

I get a sound, yes, but if I've walked away from the computer and come back, I'm still not in the habit of checking to see if I have messages. The sound doesn't really help me if I'm not around to hear it.

Okay, here's what I did today. It works great for me (Windows 11, Desktop machine), and I hope it will be a good solution for you, too.

1. Open the Windows Messenger App. Then do the following:

2. Open your Chrome and paste the link. The screen should look exactly the same as in the Windows app.
3. Click the three dots icon in Chrome's top right corner, click on Cast, save, and Share, and select "Create shortcut". The shortcut should be on your Desktop now. You can also pin it in your Taskbar and use it whenever you like to use Messenger in the future. ;)

This should open Messenger in your favorite browser and also look the same as the Windows App.

Let me know if this works for you too.

Martin