There is a bug that strongly breaks usability: when I move Thunderbird Portable to another PC, it doesn't remember which folders has "Favorite" mark. Also, I have "Favorite" option set in View - Folders menu, but it resets to "All" on another PC. Some folders occasionally lost Favorite mark even when I move Thunderbird folder within 1 PC.
It would happen for both folder and PC changes as it's likely tied to a path change. I don't use Favorites myself in TB but I think I had fixed this a while back. I'd wager TB changed the way it stores them. I'll need to look into it as soon as I have time.
Sometimes, the impossible can become possible, if you're awesome!
This appears to be working in Thunderbird Portable 115.8.0 when moved paths and PCs at least for me with both remote and local folders set as favorites. If it's not working for you in the current release (make sure you've updated the whole package and not just let Thunderbird update itself) please provide instructions to reproduce (specific paths, etc).
Sometimes, the impossible can become possible, if you're awesome!
It's good that it works in 115.8, but I don't want to update to 115.x, because it broke Manually Sort Folder addon, which breaks usability even stronger than this issue.
I'm sorry, but neither we nor Mozilla support older versions of Thunderbird. The legacy 102 build was last updated in September 2023 and, I believe, has known security issues now.
Sometimes, the impossible can become possible, if you're awesome!