Comments breaking the character limit/with pictures

TL;DR: How are people placing comments past the character limit/with pictures in them?

So I've been seeing some comments that break the character limit of 253 characters (I believe its 253, somewhere around 250 at least) and sometimes the comments are so long, that it says 'show more'. I've added screenshots of one such comment for reference.

Does anyone know how this is possible? I believe they may just give some accounts this possibility to test out the function.

The same goes for people commenting pictures by the way, I've been seeing more and more pictures being added to comments (although it is still quite rare). I've tried pasting a picture in my notes app, copying it and then pasting that into my tiktok comment, but to no avail.

So I believe this is just testing, and priviliges are given to a select amount of random accounts to do this. But, I can't find any definitive proof/answer, so I wondered if anyone here has seen something more conclusive.