i think its just the base version of software, my did a factory reset on my 26 once and it went back to 1.xxx breifly, which wouldn't have even existing in a 26, but then it updated just fine to the newest software.Many thanks. This exactly fits my situation, and makes sense if the reman battery perhaps had some yet-to-be-overwritten firmware.
(This is a better explanation than my backup which involves time travel back to 2022; I do still have some unfinished business there.)