I don't know if this is due to their changes in moderation policy, or if AI has overwhelmed them, but I vastly preferred the old news feeds
That's quite a claim.
- sex work is against Instagram TOS and they take active efforts to ban people doing it, including design features such as limiting people to exactly one offsite link per account which may not be to onlyfans
- because that's where the audience is and advertising there is effective, there's an entire industry in working out how to promote sex work on Instagram without getting banned
=> Insta ends up as part of the sales funnel despite actively trying not to be. See also Twitch. There is of course no evidence of them intentionally onboarding people into this, it's an emergent feature of being a site that posts images. Then have to censor aggressively, and even then sex work exists at a sort of "censorship shoreline".
On the other hand, Reddit and Twitter have never really cared, and only with some campaigning effort have they been made to censor nonconsensual intimate images. Twitter made its pornbot problem worse by selling bluetick promotion.
I think this has more to do with Instagram wanting people to stay on Instagram than discouraging sex workers. I'm guessing there's a long list of things the offsite link isn't allowed to be aside from porn. Hate groups and gambling sites come to mind.