For me, it’s the lack of polish and full corporate productivity suite. There are _zero_ effective replacements for a multitude of things I need, although I would be perfectly happy with a fully standard implementation of Remote Desktop (and no, Remmina still lacks the authentication and virtual desktop workspace support I need). Edge and Teams betas are coming close to providing around half of what I need, but not al…
Just in case you didn't know, since the SolarWinds debacle from last year, Microsoft has completely blocked authorisation for corpnet and other tools on anything other than enrolled devices. And since they only support managed devices on Windows/MacOS, using Linux for day job is a no go. Last I checked, circa Jan, I couldn't use Teams/Office on a web browser in Linux (of course, this might have changed in the meantime).