Yes, precisely. I rely on Thunderbird every single day, which is why I froze it at version 60-something (rolling back about four years) after the upgrades kept breaking it and mangling the appearance for me and the other people in my company.

It was a lovely mail client. It seems they're repeating all the mistakes that firefox made. Firefox added pocket, everyone disabled it and eventually the feature was removed. Firefox added chat, everybody disabled it and eventually the feature was removed.

Now Thunderbird has added chat, that's great. What does it support, Slack? no. Discord? no. Oh. That's not great, then, that's useless. They're intending to jumpstart a chat protocol with a client that's used by like 0.8% of users? Sure.

The last update made the context-menus and dropdown-menus white backgrounded menus with literally no border, so you had no way to determine where the menu background ended and the email background started. That was the update that pushed me over the edge and prompted the rollback and push of whatever 60-ish version I chose. My staff need imap and calendaring and consistency. That version delivers.

I have absolutely zero interest in playing the 'what spurious UI change will throw my staff into confusion today' game with a basic productivity tool.