Since October I've noticed that these episodes have been slowly picked off Paramount+ in Canada - in my province at least.
Given the current political climate I can at least think of a reason why they would ban the last 3 to theoretically avoid controversy (then again if they're banning specific episodes due to antisemitic themes you would think The Passion of the Jew would be the first to go, but those are still up lol), but I'm sort of puzzled as to why the first 4 have been taken off? I don't remember anything in these episodes that would warrant them being removed over any other episode. There are plenty of worse ones out there, why do you think they removed those?
Almost all were removed because of threats made by Muslim extremists over the depiction of Muhammad. Most only aired a single time on TV, and most, if not all streaming services that play/played host to South Park have never had them available.
You can, however, watch them on the home releases. They're all there in the box sets, which I'm happy to own.
In fact, Paramount has some nice box sets, which are the ones I bought. S1-5, S6-10, S11-15, S16-20, S21-25. That's how the box sets are split. The specials aren't included in the regular season sets, but they are available as well.
This sort of sounds like an ad, but it's more about the importance of physical media. They can't censor what's sitting on my shelf.