I don't know what you mean by this comment. Can you elaborate? Are you talking about the window border?
Also, even basic Explorer windows often lose their borders when logging in via RDP, leading to white on white mayhem, but I've always assumed that's a bug.
It would blend into Teams, where only a hideous "high contrast" mode would render borders. The list keeps going on and on.
I've used a registry "hack" (manually added a setting) to set the colour of inactive windows, this does improve things a bit when it works. I prefer eg a dark grey as inactive, and eg orange for active window.
I'm blocked from upgrading my work PC to Windows 11 unfortunately.