From what I had read, it seems like it’s done by letting people command AutoMod (or a different bot account that has Mod access to the sub) in the comments, similar to how people would use the RepostSleuth or RemindMe bots. So unfortunately, this probably dies when the API gets murdered at the end of the month.
Shit like this is why I switched to a third party app a while ago. I used to have the official app on my phone because iOS and everything I remembered seeing as far as 3PAs went was all for Android before I heard of Apollo. But the fact that I was seeing “posts” like this every three-or-so posts, and the fact that they were all over the comments as well was just way too much.
It’s exactly why I will not go back. I have like three niche subreddits saved that have no real equivalent in the Fediverse and I’ll only check in on occasion. Through Old.Reddit. With a browser that has an ad blocker built in.