+1 to what others are saying, I also left a negative feedback in OWA.
I never dedicated time in the past to participate in community posts but this UI change was the straw that broke the camel's back and made it necessary for me to echo the same dissatisfactions as everyone else here. At least give us customizability and options!
I logged in to this change a few days ago and thought it was a bug until I saw the buttons way over to the right just a few minutes ago, prompting me to search up this post. I know right? I didn't see it for a few days, it's almost as if important functions that we've been used to for years such as, I dunno, quick action buttons or something, shouldn't be placed that far off on the edge of the UI. The new placement is such a time-waster and makes finding and clicking on the right one like crossing a 10-lane highway! Better make sure the button you're hovering over is aligned to the right sender or subject! Hey, at least they had the courtesy to highlight the row! Oops, you pinned the message instead of flagging it because your mouse moved a bit to the left when you were double-checking the subject? Tough luck, at least you seem to be productive by modern standards, because more clicking and more time staring at that email equals more productivity right? geez....
And no, MS, I cannot simply install the desktop app on my institution's computer.