Thunderbird Release channel version 146 brings fresh regressions directly to your desktop. Check them out, blank parts of the UI and inconsistent naming:
This bug was reported by Thunderbird's internal QA team, good on them, a volunteer developer fixed the issue, and Thunderbird's release manager refused to ship the fix in the Release version. It's a bit like in this Dilbert cartoon:
And the folder name saga continues, this was already covered here. Mileage varies depending on mail provider and localisation. Here shown for a Gmail account. On the left, the folder tree, on the right, the folder name in the Subscribe panel, which is typically the folder name shown in the provider's web UI:
Follow-up here.