I have just auto-updated Thunderbird to 115.3.3 (32-bit). In my opinion, it is a mess. But leave that aside. After a lot of messing around I was able to bring colours and fonts to something resembling the prior version's scheme. However, now, any time I open an e-mail into the reader pane, it always has the background painted medium gray, making e-mails un-readable. I have searched high and low for a means to set the background back to white, but cannot find one. To me, the resulting unreadability is so high that I will seriously consider leaving Thunderbird for something else unless this problem is fixed immediately. Yuck.
Me too. I have two W10 PCs and the display is different on them. One looks "normal", the other is impossible to set to usable fonts. Sent messages arrive in a tiny font. I have already switched to eM Client and I am very happy with it.