Ah, thanks for clarifying those details. Things make sense now. I did change the new user TL and the summary settings at some point – just thought bootstrap was some kind of background override.
(I searched, but couldn’t find official documentation for bootstrap mode. Seems it’s usually described in posts here as “it gives the first 50 users TL1 and daily digests” without explaining the mechanism. This leads to some misunderstandings.)
I did, thanks – the Getting Started admin guide likewise mentions the effects of Bootstrap mode, but not the mechanism. This left room for me to assume that Bootstrap mode was a background rule overriding admin settings, not a direct temporary change to admin settings. So as I explored these things independently, it didn’t seem to add up.