If only there was a summary of said article right here in the comment section, not even a click away

All this just proves that Christians don't know the first thing about astronomy because the actual date of the solstice flips between the 21st and 22nd of December. Which should actually be the 31st and 1st according to the original intent of the calendar, as said, Christians have no clue about Astronomy and allowed the thing to drift.

It should be noted that many Orthodox churches have actually been using 25th December as the date for 100 years now, following the 1923 Council of Constantinople. The choice to shift to the Gregorian date (or rather the Revised Julian date, but it's the same day as the Gregorian one) is just a shift to align with other Eastern Orthodox patriarchates rather than a departure from Eastern Orthodoxy altogether

I’ve never seen a comment that would benefit from autocorrect so much.

Orthodox churches are kinda special in the sense that they're very oecumenical, don't go around saying "XYZ isn't true Christendom", venture outside of their territory only carefully (e.g. to serve migrants who happen to be orthodox, but actively avoiding becoming a promiment church in those areas), but OTOH also tend to be staunchly conservative when it comes to their own traditions. They're not centrally-run like the Catholic Church, while Constantinople holds a special place individual territorial churches are self-ruling.

So when e.g. Lutheran Churches say "Everyone is a priest, so obviously women too can be reverends", Rome is writing bulletins warning their own believers of participating in "so-called sacraments" in "erring churches", whereas the Orthodox go "nah we're fine as we are, thanks but no thanks".

Splitting off from Moscow is indeed political, also, complicated, also, partly theological (because ecclesiastical jurisdiction), there's two major branches: The re-constituted old Kiev patriachate, dating back to the 90s, (Moscow back in the days dissolved it without even asking Constantinople which readily accepted the reconstitution), and an organisational arm of the Moscow patriarchate which declared independence form Moscow in the wake of the invasion. That's also the one with the spy monks though not all of that "we're independent" talk is necessarily a front the church has, aside from political hacks, also actually religious people in it. Shocking, I know.

Switching to a different calendar is theological but Constantinople certainly won't care short of saying "nah we're fine". It's, after all, what "autocephalous" means.