@ Energy X:
If you have a site and you change hosts, you typically don't leave a copy behind at your old host - you want people to use your new host instead. If the wiki community had actual control over its site, this would have happened. But there are quite a few hidden costs with "free" hosting, and keeping this wiki after the fork was one of them. It's just reality that an external entity (FANDOM) has control over this wiki.
"Who are you that dictates what should or shouldn't exist?"
I'm just an editor? Look at me, DICTATING and DECREEING and MANDATING (as per your reply). I can use fear-mongering buzzwords too.
I don't know why you continually reach for the ineffectual "Yugipedia plagiarized" talking point (actually, we both know why). The content was immediately reverted upon being made aware of it, with the offending users being warned. And said users know better than to do it again. If you see evidence of it happening again, you are free to contact us about it and/or personally revert the offending content.
"The users here that copy content are reported and blocked."
Oh really? Then I hope you don't mind reprimanding ArcadiasScholarly (Italian) yet again, for what really should be the final time. When are you going to learn, when it comes to this user? They were perma-blocked before for good reason.
Don't criticize Yugipedia for copying when you yourself do nothing about this wiki's copying - it's embarrassing that Sannse from FANDOM had to step in personally. If you don't want that to happen again, then deal with it yourself, effectually. And remember that while you can disagree with FANDOM, you can't ignore FANDOM's wishes, as they own this wiki (and they're not Yugipedia, so vent your problems with them elsewhere).
@ Pitifulheartles, it'd be interesting if you could revisit your behavior here in 5-10 years from now, and reflect on your need for drama. You're the one who wanted it, as you unnecessarily tagged me. I'm only replying here to provide the other side of the story.
To answer OP's question, the security certificate was renewed at the start of the year, which is likely related to what you experienced.
Regarding the separation: The majority of dedicated editors here decided to move outside of the control of FANDOM, since FANDOM was pushing unwanted changes here (from our perspective). Ideally, we would have "moved" the wiki in its entirety elsewhere. But FANDOM rarely deletes leftover wikis that have 'forked' (especially wikis as big as this one), so this wiki was left alive for anyone to contribute to.
AKA, this wiki really shouldn't exist anymore (because of the majority vote of the wiki community to move to Yugipedia), but FANDOM has the right to keep it alive.
Yugipedia is this entire wiki (until the date of the fork in 2018, where the edits splinter off). There were no significant differences between the two, except appearance and ownership. And yet some people chose to stay behind here, on FANDOM. That's fine.
What isn't fine, is that some people here want to pretend the fork has no purpose, and take Yugipedia's new (unique) content as their own. That's not right, considering that individual people decided to contribute to Yugipedia instead of FANDOM. If a person wanted their contributions on FANDOM, they'd publish them here instead of Yugipedia (or publish them in both places).
No one's being a bully here. This Fandom wiki has nothing that Yugipedia wants, but apparently Yugipedia has a lot of stuff that this Fandom wiki wants. We moved away from here because we don't want to help FANDOM anymore. If our content is being copied over to this wiki, then what was the point of editors moving to Yugipedia?
Since some people here were copying our newer content, I thought that was inefficient of them, and asked some of them if they'd rather edit Yugipedia instead. And a select few people here reacted like I spit on their faces.
The actual reality is that (some) lingering editors here probably wanted to be in charge of what's allowed on this wiki, when it wasn't allowed under previous management. And a select few don't like that Yugipedia has more dedicated editors producing more bountiful original content (in some areas), so they advocate taking that pre-made content from Yugipedia.