Get a cheap VPN like SurfShark VPN (follow my links to get 82% off - just kidding but I do use them). It's perfectly safe to use a cheap VPN like that if you're just trying to hide yourself from non-governmental actors to keep your private info private.
Much easier to let them operate and collect taxes on them and then send the normal police when you want the data they so conveniently have collected and organized for you.
If you add a private salt, you won't be able to do "grouping" or identifying duplicates, which is what this thread was discussing.
If it was me, and I wanted "independent" researchers to highlight clusters or duplicates I would do the following as a first-pass solution:
Store an internal mapping of IP->unique sequential number, likewise do the same for usernames. The goal is that it's random and not based on any hash or ordering. So people with either the IP, username or username + IP, can't identify the unique internal numbers.
Then release those. Though tbf, if I was part of any sort of "bot prevention" or "sock puppet identification" team at Reddit, I'd be doing this already. But we all know the dirty secret is to not actually track down such abuse, but to appear like you are doing so, so that you can inflate your user count with plausible deniability.
But I would very much want to see the IP addresses each account used last time, to identify people with many alt accounts