Thunderbird 140.0 (currently at 140.5.0esr) is the ESR version while Tb 145 is on Release channel. and were released within a day of each other in November.

ESR is short for Extended Support Release as they get stability and security fixes and no new features or such.

As you can see on https://www.thunderbird.net/thunderbird/releases/ the Thunderbird Releases used to be done in a ESR fashion for a long time until Releases started again as of Tb 136.0

OK so i strongly suggest... that the flatpak option be CLEARLY noted in the repository it is ESR. This is currently not that case. As an end-user I have NO WAY of knowing this by the package repo naming. NOR is ESR qualified under Windows OS, when I install Thunderbird I got 145, when I install in Linux I get ESR 140, how do I avoid this?

Please clearly denote this difference and allow the user to pick the ESR or NON ESR version... with a warning that Windows is NOT ESR by default but Linux is(?) I trust you understand my point?

With Windows you would download Thunderbird from say https://www.thunderbird.net/ or https://www.thunderbird.net/thunderbird/all/ where by default you get served the current Release.

If you were to go to those page while on Linux you should get served the tarball version of the Release.

On Linux you may get a extended support version of an application if available instead of Release with the various ways you can install a app whether it be by flatpak, snap, a package build by deb or rpm etc.

I do not have any control of what the Thunderbird people do with Thunderbird versions and how flatpak version is served as I am just a longtime moderator here on this community support forum.