I don't know. I'd imagine any registrations or licensing the government required would get revoked which would have direct and indirect consequences that prevents the church and its clergy from either practicing, preaching, owning property, etc... Those there on a work visa get sent back and so on.

I don't know the specifics here but usually this means they are not allowed to practice anymore. If they had any sort of state exemptions or privileges they'd be gone as well of course. I don't think they can legally arrest them unless they circumvent the ban.

I don't think they've banned Orthodox Christianity. Just the specific church that happens to be of that faith, because Russians are hypocrites who bend international laws as they see fit, and this specific church is connected somehow.

A large majority of Ukrainians are Orthodox, but they are divided between two main groups with similar names: the UOC and the Orthodox Church of Ukraine, which would not be affected by the legislation. Many Ukrainians continue to call the UOC the Ukrainian Orthodox Church - Moscow Patriarchate, as it was commonly known, despite its recent claims to independence.

https://apnews.com/article/ukraine-parliament-legislative-ban-ukrainian-orthodox-church-539e0f3a6d657277aa4fa93b8ec53505

So there's still an Orthodox Church in Ukraine. The names are similar, but not the same. Sort of like the two Chinas. One calling itself the People's Republic of China, and one the Republic of China. The latter being more commonly known as Taiwan.

It's almost that bad. You do not celebrate orthodox Christmas day on Jan 6th, no, you do on Dec 25th