I was unable to replicate this on Safari 15.1 (17612.2.9.1.20), FF (95.0.2), or Chrome (96.0.4664.110) on an M1 Pro device (OS 12.0.1). Video playback appeared normal, identical to an x86_64 device.

Confirming (a) that I can replicate the issue following Suffusion's report above, and (b) I encountered the issue "in the wild" when attempting to vote. I use iOS, Chrome, and the Monobook (responsive) skin for what it's worth. I was able to vote by changing back to the desktop view on VoteWiki IIRC.

I don't believe it actually uses the preferencestoken either - the change to the API certainly doesn't appear to have broken anything. I'll submit a patch to remove the retrieval.

Hello! Closing this as resolved as I am still maintaining this and there's no point having this task open.

For what it's worth, this bug breaks the current implementation of FireflyBot's task 11 - notifying authors of drafts on enwiki that they are coming up to the point where they can be deleted. I realise that's a very small matter in the grand scheme of things, and I can rework the implementation around this bug, but thought it worth noting that the bug has "real-world" consequences, even if very tiny ones.

@Peachey88 Yep, that's the method I used to create the account.

Should the Wikitech account have been created automatically? The instructions don't specify creating one manually...