FYI, Thunderbird 115 is getting released tomorrow (July 11). Right now, if you visit the Thunderbird website [1] or try to look for updates within the application, you won't find this release version available (you can always get the beta release from the website).
I would advise against installing the beta for anyone considering it. I was in the beta for 2 years (mostly because it's quite challenging to get out of the beta), and the quality of the beta releases leaves a lot to be desired.
Aaaah. So that's why I wasn't finding anything, I thought I was going crazy. That landing page seems to hint that it's currently available ("Upgrade to version 115 and experience the future of Thunderbird!").
[1]: https://www.thunderbird.net/