Not to be an ass, but this is the weakest counter explanation I've seen.

That is an edge flapping around & even crinkling/folding slightly & even dropping down & covering his tie knot... and it even looks like the same thing (a loose/detached, moving edge) in the video you provided.

Plus, you are using other examples from within the last few months, i.e. dates where he may have already been arrested & body doubles already deployed. Everything since beginning of Covid is suspect, since we've been hearing about arrests for that long or longer.

Show me this happening in his interviews from 4 years ago or another old normie's saggy neck producing the same exact illusion, and then I will believe your argument is much more plausible. I will bet you can't find anything other than other people wearing masks. (Mainly physical, but also possibly digital.)

Until then, "his neck is just like that" is a weak & unlikely argument:

i.e. "just" makes overhang shadows that would not be visible in a studio lighting setting from that angle unless A) there is a deep shifting crack that goes into or under his neck surface, or B) maybe unless his collar is so tight & digging into his skin sags so much that he would literally be visibly uncomfortable & pulling at his collar or somewhat choking--which is not the case, because he is not giving off those signs... And even then, the shadows would still not produce the exact same effect shown here, as the rounded skin spilling over the edge would produce a round bevel that creates a less sharply contrasting gradient all the way around the the neck as opposed to just at the tie area in addition to producing a noticeable spread & diffuse shadow on top of the collar/tie knot as opposed to just underneath or where edges meet.

It "just has" an effect that would require a highly specific situation to produce. Sure.

I don't understand how people can mistake these visual things that just look so obvious to me. But I guess I have the advantage of very accute visual observation & rendering skills thanks to my 2 decades of fine & digital arts training on top of being an optical scientist. Like that whole blue dress thing... Seeing things for what they really are & what optical mechanics actually produce visuals has always come easier to me than most. With all that experience, this looks so, so much like a flapping edge of a layer on top of the (actual) surface to me.

Spez: If you pause at the right time, you can even SEE THE SKIN UNDERNEATH THE "SKIN."

Spez 2: An AI CGI edge rendering error, as someone else suggested, can also create that effect (the edge of a mask flapping & wrinkling), but you are less likely to see shadows matching up to those. It will fall into the uncanny valley, & I would expect the contrast to be more jarring in places. I still think it is more likely to be a physical mask with the faint shadows I can see following the movements of the edge. I would probably need a better quality video to better make out the difference between mask & AI. But AI would be my next best explanation.

Most likely a combination of physical/mechanical & digital methods zipped together with AI, and the physical mask failed & was too far off for AI compensate for it (or AI also failed).