Just a wild guess but I’m thinking Reddit doesn’t actually host the content. It’s all links to a 3rd party like redgifs. Meanwhile Tumblr has the content stored within their own servers.

I was going to say Tumblr’s owners care more about optics and it was more popular with teens (so more parents knew about it), since it was-is a home to many fandoms. And, in general, alike to Twitter, you don’t get locked in your personal bubble as much as you do on Reddit, there’s many ways a viral NSFW can get into your feed.

But, maybe, it’s just when they got punched, how they were prepared to it and how they are perceived. Reddit got it’s warning about CSAM long ago, it wasn’t the first nor the lsst their scandal, and it’s seen as a shithole for unemployed adults anyway, for Tumblr it happened in 2018, after internet got taken way more seriously by public, especially how it’s bad for kids, and that’s where your kid goes for their daily shipping content.

If you read their lists of controversies and dramas side by side, reddit was blamed for many political and criminal ‘adult’ activities, and tumblr was mostly blamed for being a bad influence for minors, making them harm themselves, consume porn and get toxic to random artists.

Because the rules aren’t enforced equally. There’s really no other way to put it. Twitter too. They’re big enough that they get special treatment.

App Store and Play Store approvals are famously capricious, with little room for appeals. Take a look at this nightmare of trying to get an app approved for OwnCast, the Fediverse version of Twitch.