i think there's this romantic notion that rpf could just revert back to the 1960s star trek/beatles grass roots fanzine mailing lists, but the actual origin point of the broad rpf spaces we have right now - inherently high-access, multi-platform - are more like harry styles imagines on pinterest. rapidly consumable, platform-agnostic. "keep fandom in fandom spaces" is a nice line that gets across a clear ethos on a peer-to-peer level, but on a material level, fandom is now an asset self-sufficiently generating value. it might not be your fandom space, but everywhere is a fandom space.
everyone who has rpf written about them knows about it. it's white noise to them, just one of the top twenty things they get harassed about every time they exist as a public figure. max verstappen hears ddu-ddu-ddu yelled across the street at him sometimes, and sometimes he sees art of himself making out with george russell in a maid outfit. if you feel any worry about them "finding out", or changing their behaviour, or making them uncomfortable - they already know, and they are uncomfortable. like, they really know. they've never not known, actually. the current push towards low-budget, "naturalistic", fandom-dependent social strategy actually requires them knowing.
the ferrari fanfic video gets brought up a lot as "too far", but i do think there is a lack of perceptual awareness in fandom that all personality-based content these teams post is targeting rpf audiences to some degree, because everyone is an rpf audience now. there's less space between a person who thinks it's nice that two teammates get along and a person who writes omegaverse than you'd think, as far as audience retention goes. do you ever wonder why lando and oscar always play games in the mtc lobby where people can walk by? it's not because mclaren can't afford a backdrop. low-spend content that is perceived to be "real" performs better, no matter how staged or implausible the scenario, how tenuous the tie to the sponsor paying for it.
the true rpf fan, and the majority of rpf fans now if you were to study broad patterns of fan behaviour, is exterior to fandom participation entirely. they're defined by their identities as consumers of content. for those fans, fan-generated and official content become drops in the same bucket. those fans have post-notifs on - for their favourite fic author, for their team's tiktok. they consume and circulate content at high volume, which means that algorithm-based platforms detect early high-yield engagement, those metrics push content wider and drive monetization, and now dell computers is really glad lando norris knows most of the words to taylor swift's love story. wait, why did dell want them to do karaoke, again?
as a case study - have you ever felt like you arrived to a fandom early and had nothing to engage with, but you didn't quite love it enough to make the content yourself, so it was a dead end? now that fandom itself is an accumulating asset, there is an economic incentive to making sure that doesn't happen. it's mainstream now in the music industry to "plant" fake fan accounts with false identities that model what their ideal fan behaviour is, in hopes that real fans will come along and join in. i know someone who was contracted by a major label to run five discreet fan accounts with different names, personalities, schedules, posting habits, and backstories for a new artist they'd signed. their job was to make all the fan accounts pretend to be friends and post "unofficial" fan-shared content for each other, to simulate that this was a fandom that already exists. part of it included faking speculation of rpf rumours in the artist's inner circle. all of this was paid for with company dollars, and it worked. i'm not saying any of the blogs you follow are secretly mercedes pr - if you're on twitter, i'd be less sure - but what i think is of value there is that the "ideal fan" who's behaviour social teams are trying to model, so that other fans follow along? that fan has really bad fandom etiquette, actually.
so if you're like. uh, tumblr user minisector, we're not talking about rpf anymore, that's just marketing. that's kind of the point. if you want to moderate fandom behaviour - ⬆️ this is what you're trying to control.
i think discussions about fixing rpf fandom behaviours fail primarily because of the instinct to always externalize. it's a solid instinct - for thoughts on "rpf" being an external phenomenon to rpf fandom, see the previous eight paragraphs! the instinct to blame the worse fan, to moralize about the rpf subjects, to want better for the writers who contribute and make fan spaces better, doesn't have to be a wrong instinct to simultaneously be a convenient vantage point that lets everyone reblogging that opinion off the hook.
it'd be nice if there were a "new website", but that wouldn't actually kill off any of the things that people object to. the enemy, weirdly, isn't the rogue commenter referencing a fic on someone's instagram. the person "breaking containment" - that person makes you cringe, you wish they didn't exist, but they're not what you'd actually change. that's plucking a leaf off of a tree with infected roots. and anyway - every driver's social media comments are moderated to some degree, and those comments always stay up.
even the fic authors who keep themselves fully locked away - even if they only ever wrote in their notes app - are engaging with the topic in the first place in observance of that same feedback loop. engaging with rpf at all - ao3 hits, the mutually beneficial galex pr friendship, sending a friend a challenge video, downvoting a guy on reddit arguing about who the goat is - makes you an instrument in spreading it. none of us - no matter how active, passive, conscious or unrestrained - are hard endings where the things that makes this uncomfortable or strange fully resolve.
you know that truism - how an apology isn't for the person you hurt, it's so that you can feel better about yourself?
when you worry about rpf getting out, who are you worried for?
my suggestion: archive lock your fic, make your blog publicly unsearchable, create for your friends and take care of them too. make a conscious choice not to interact with fans who don't. not because it's the right thing to do (it is), but because when containment inevitably breaks, which it will, having made an active, actionable choice about how you've participated grants you the agency to be less worried, embarrassed, or sorry about the outcome.