To be honest, I agree with you.

I was never very active in the gender critical / LGB parts of Reddit. I moderated a couple of subreddits around niche interests, and for the brief period where I was part of Reddit (about two years) I was a very active Redditor, spending hours every day falling down this rabbit hole or that rabbit hole. If you avoided the default subs, you could get away from divisive US (let's be honest) politics. Looking at peoples' collections of fountain pens, or discussing why my croissants were chewy, or asking what language that sign in the back of that film was in were all excellent ways to while away the time.

I noticed that this all changed in around February 2020. The US election was doing whatever it does at that time of year (Caucuses? Primaries? Town hall? Whatever the first stage is called) and things were not going well for Bernie Sanders. Reddit, apparently, couldn't hack that. Couple that with the escalating COVID-19 pandemic, and you had a perfect storm of political bullshit, and it was everywhere.

Donald Trump is single-handedly murdering American citizens, but if Bernie had been president not a single American would have died or lost their job, poverty would be eradicated and American citizens of all classes, creeds and colours would have joined arms in a spirit of brotherhood and danced in a circle around the Capitol building singing 'All you need is love.'

Okay, /u/FeelTheBern2020, but I came here to talk about The Booker Prize winners. I don't care about Trump, keep that in the politics-aligned subreddits, please.

LOL Karen can't get a haircut why is she protesting in the middle of a pandemic what a selfish fat hick look at those DOMESTIC TRRRISTS outside the Michigan (?) capitol building they should all be shot why arent the police arresting them

Then, of course, George Floyd died and Reddit went into full All Cops are Bastards, Riots are the language of the Unheard, Property can be replaced but lives can't, woke meltdown. Rioting was valorised as a noble act, speaking truth to power. Burning down a police station (regardless of whether people were inside or not) was perfectly acceptable under the circumstances.

Don't post about it on social media, otherwise the pigs will know where you are! Let's cordon off an area of Seattle and secede from the United States so we can create the Black Utopia this is all in service of. The deaths of nineteen people, thousands of arrests and literally billions of dollars in property damage are all perfectly justifiable as long as I agree with the people doing it.

The notion that protesting during a pandemic was selfish very quickly evaporated.

But what's this?

Some right-wing people are using the 'fiery but mostly peaceful' protests as cover to cause trouble? This is outrageous. These 'peaceful protests' have been taken over by white supremacists, and all the rioting was their fault! Rioting is wrong! Destruction of black-owned business is wrong! People I don't agree with aren't allowed to riot!

And then came the purge, and my last fuck about Reddit went up in the smoke of that police station.

In answer to your question, I don't know what caused Reddit to turn into the cesspit that it is today. It's possible that funding from Tencent contributed to that, but the amount of anti-China bullshit that was floating around there would seem to suggest otherwise.

I think Reddit, like other platforms (Facebook, Twitter etc.) felt empowered to take ownership of the public square.