I hope that doesn't happen. This would doxx me by tying my "public" accounts to some of my private accounts.

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.

I have this theory that every single one of these VPN services is operated by the secret police of some country.

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.

Unfortunately this often results in a shadowban on Reddit. So it's fine for lurking but not interacting.

What you’ve got there is a list of accounts that access reddit from behind a NAT with a few sock puppets thrown in for good measure.

Hash of the IP would be sufficient for that purpose and would keep location anonymous.

IPv4 isn't that big. You could compute the hashes of all addresses on consumer hardware. You would want to add a private salt.

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.

Works just fine with a keyed hash (same key & IV for everyone).

Just make sure to remove the NSFW accounts to avoid future "incidents".

shouldn't that be easy with some stylography?

Minor correction: I think you mean stylometry.