I am using version 102, all is nice. From my perspective all thunderbird needs now is be be a little less bloated. Currently it takes 90 seconds to load thunderbird on a quadcore system @3.5ghz and 16g ram on WD black hard drives on a raid setup, this is before any email headers have downloaded for text only meassages. every subsequent release is taking longer and longer to load, it's not because of virus or infections etc there aren't any. It's not from plugins either because i dont use them. (I Have been a user of these products since the days of netscape being king 😉 ) Everytime there is a software update I am reminded of something George Carlin once said, words (and analogy in this case) to the effect of: "Some one own a house and fills it full of stuff, then they relalise there's no room left, so they go buy a newer and bigger house, then they fill that house up with more stuff, so the cycle continues." In this case the house is the compter and the stuff in the software. 😉
Downgrading thunderbird to version 78 solved the startup issue. Today it was painfully slow, hence the down grade. The issue with newer versions only happens after the PC is started up the first time for the day or after reboot.