
https://www.thunderbird.net/en-US/thunderbird/144.0/releasenotes/
Thunderbird 138.0.2 fixes:

https://www.thunderbird.net/en-US/thunderbird/138.0.2/releasenotes/

What is fixed:
“It’s basically a complete redesign of how you add accounts (like email, calendars, etc.) in Thunderbird. The old setup system worked, but it looked a bit dated, could be confusing with its tab-based approach (easy to accidentally close!), and wasn’t very consistent across different account types.
The Account Hub aims to fix all that. It provides a single, unified, modern-looking wizard inside a pop-up window (modal) to guide you through setup. For brand new users, this modal will guide them without letting them get lost before their first account is ready.”

> hg version
Mercurial Distributed SCM (version 6.9)
(see https://mercurial-scm.org for more information)
Copyright (C) 2005-2024 Olivia Mackall and others
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.> ls -l
total 16
-rwxr-xr-x 1 chris chris 16025 Jan 17 18:13 bootstrap.py
drwxr-xr-x 1 chris chris 2264 Jan 17 18:14 mozilla-unified
The whole building process lasted approximately 8 minutes on my AMD Ryzen 9 7950X3D 16-Core Processor and required 30.1 GiB (32,355,790,419), 1,401,719 files, 138,437 sub-folders



More details at https://developer.thunderbird.net/thunderbird-development/building-thunderbird