It's been heading right or center-right ever since the_donald (2015), r/conservative, etc have gotten so huge, if there's been any political shift.
Do you really think you'd regularly see white supremacist content on reddit in 2006 as often as you do now?
It was really obvious when something unexpected happened, like that video of Hilary collapsing and having to be pushed into a vehicle during the presidential campaign - for several hours the sockpuppet accounts didn't know what to say so comments from regular users started making it to the top again.
(Quick edit, had the wrong organization in mind before)
In case anyone is in the same boat as me, heres an article on the subject: https://www.thedailybeast.com/hillary-pac-spends-dollar1-mil...
And yeah, it's probably not them but it definitely feels like something is still going on. In the Chicago subreddit, for example, on anything that touches a politically-charged topic, the comments and votes will be exactly opposite what they might be on a different day.
Same thing happened after Trump's 2016 election win. For a day or two, it was possible to post something non-leftist to /r/politics without having it be mercilessly downvoted; as if the shills were awaiting orders.
Wait - you seriously and unironically believe reddit has become _more_ rightwing in the past 7 years?
For example, I used to love /r/conspiracy which is now rather overrun with a particular kind of conspiracy theorist and I no longer feel welcome.
Speaking from the gut I'd say more communities have slid to the left than the right, but nearly all of my communities have been more politicized and it reduces the amount I use the service considerably.
/r/all is populist as ever, but Reddit as a whole has simply fragmented. For politics specifically, non-progressives just live outside of /r/politics. Neoliberals tended to hang out in /r/political discussion, Trump supporters in /r/the_donald, neoconservatives in /r/tuesday, etc.