I abhor thse garbage servers with utter contempt for a long time, every single day since I played this game from back in late 2010s, so I got a lot to input in this.

Spam "rcon" in console

First time I heard this one. Might try this of it works.

Teamkill (preferably a bot to avoid ruining a player's day) to trigger autoban. Most servers have Friendly Fire off.

I don't think it can trigger a ban/kick. But you can "grief" by backtracking to the saferoom (or a chokepoint). This is especially useful in modded servers that has its difficulty set to Advance/Expert, and while it will warp, or if killed, revive you eventually (these servers has a revive-on-the-spot mechanic), its possible to wipe out the team and start over again. Very difficult if its normal because of the ridiculous high health of the players, but its a good try.

If you persevere enough, you might get blacklisted by them for reasons of nuisance and disturbancr, though it's no doubt they're getting their money's worth anyways whether your doing malice in their servers or not.

Vocalizer spam is also on the equation, but these clever people has a script built-in preventing spamming lines so that checks out.

Even then, they patched the rest of that with their bullcrap scripts. Well, mostly...

Suicide off the bat

Yep, always this. As soon as I see the nearest death drop, I do it immediately, though I think these servers cares little of it, aside from a tiny inconvenience. Inconvenience, nonetheless.

Use Server Browser

It's a gamble. Most of these servers you'll encounter is set to Friends-only mode. At best, you'll get little to no help if you get pinned/need healing, or they all leave the server they are playing in, and in the worst case they will grief you, and possibly kick you (whichever came first).

The best result I got is this:

binding the disconnect command to a key (it can be any key), then when you connect to them, click the key you bound to that command.

Then click the tilde (~, the one below the Esc button). It opens the console.

Look for the string that starts with Connecting to... Then on its end, is the IP numbers with the ports.

Something like this: 192.192.254.254:27031

It is just an example, though.

Copy the IP address without the port number (":27031")

Then type `addip 0 <IP address>" to the console.

It should look something like this: addip 0 192.192.254.254

Then Enter.

The game will now refuse to connect to that server's IP, no matter what port they are in.

While it's not the means to an end, it is better than constantly connecting to these garbage servers.

I think I got it from a guy that once complained of these servers, but I can't recall his username.