One example I have is the university breaking their VPN on Linux. They moved us from an open source VPN to some proprietary crap but I found an open source client that worked on Linux. Then they did something on the config that broke that client, and IT told me to use the proprietary client instead. But the proprietary client crashes if you even so much move the window slightly. So I gave up, and just use my Windows partition instead.

Stuff like this is why my Windows partition still exists. I’ve also thought about getting a cheap Mac Mini for this sort of thing, and for dealing with the MS Office suite when the web version craps out (as it often does).

Why their devs choose to upgrade toolkits this way I cannot say.

I forget the exact details but iirc Evince was a special case because rendering PDFs in GTK4 was so different that they essentially just had to rewrite the whole application. I think Gnome Papers still doesn’t support the full feature set that Evince supported (although it works well for most use cases now). This is why its still not the default for Gnome, although I think Ubuntu has decided to adopt it a little early.