I installed the official Reddit app and went on it to see what the old place was looking like now. My inbox was filled with spam. The "home feed" shows subs I never subscribed to. There are so many ads. Between the ads and the the extra subs in the feed, it's hard to just scroll. I also noted a lot of spam in some of the subs. Maybe they are subs with no mods? I'm not sure what's up with that.
It doesn’t matter that you IP is periodically changed by your ISP. They will always be from sort of the same ranges, as IPs are regionally distributed. That’s what a digital fingerprint is for. The mix of browser configuration, screen size, OS version, IP, and specially if there are tracking markers (referral from other websites when you click on a link directed to reddit). Also, there are tracking cookies, you might delete the reddit cookies but there are still other tracking sites cookies that reddit can use to identify you.