Can't access Chat tab anymore - "This app cannot be found."

While in the Teams 'Chat' tab on my Mac, I tapped on some "Copilot" button that was showing at the top of the window that I hadn't seen before. I was immediately taken to the 'Apps' tab, and a modal overlay displays saying "This app cannot be found." I'm fairly certain our company doesn't provide us access to Copilot, and that's why it doesn't show up in available apps anywhere, so I don't know why the button was showing in the 'Chat' tab in the first place if that is the case. But now, any time I try to return to the 'Chat' tab, I get redirected to the Apps tab with the "This app cannot be found" error.

I've tried simply exiting and reopening the app. I've tried uninstalling and reinstalling. I've tried uninstalling, then deleting all the Teams-related folders I could find in "/Library/Microsoft/" and "/Library/Caches", then rebooting my computer and then reinstalling, and still every time I try to access the Chat tab on this device, I get the same modal overlay displaying "This app cannot be found."

I can still access 'Chat' fine on other devices, and haven't seen that Copilot button that started this mess anywhere else on my other devices.