Not your ISP. Google likely is the one following that. If you have uBlock Origin installed, click on the badge on any site and you’ll see which trackers there are. For Lemmy, it’s just going to list other lemmy instances. When you’re on that forbidden site, see if they have any Google analytics trackers - those are what will fingerprint you.

Then go to amiunique.org or hidemytracks.eff.org and see what information you’re giving up. Vanilla FF gives up fonts, sound card info, and graphics info, which are enough to pin you to specific hardware. If your machine isn’t extremely common, then Google knows it’s you.

Why not download the Mullvad browser? It’s free, and you’re paying for its development if you’re paying for the VPN.