phpBB will assign you a randomized session if if you visit it anonymously (without logging in), and will serve the page to you with that sid param added to all links. Using that link will load a page without the sid param appended to links, because the system assumes you have a session I'd saved in a cookie since it saw you have a sid, even I'd you don't have/didn't send a cookie with it. Following any of those links starts the chain over if you aren't sending a cookie along with a sid, which the AI scrapers never do so they can't easily be blocked by that, and a new unique sid is generated, and all the links have the new sid appended.
Every page with a unique set of params and values needs to be investigated, because it can be an entirely different page, so AI scrapers will scrap forever, always finding more and more URLs to harvest, even though they're all duplicates of what they already have. It's easy to have multiple scrapers stuck going through a very small bulletin board continuously.
Maybe they've gotten smart enough to deal with this situation in the last few months, or maybe they put in a specific workaround. I ended up just throwing the site behind cloudflare because spending time trying to outsmart AI agents in a battle of escalation doesn't seem like an effective use of my time.
What really sucks is e.g. Gemini that pulls images without being able to go to the source (unless it changed recently.)
Edit: I didn't read "logs"
Any answer to that along the lines of "do something more complex" or "optimize your site for load" to be able to deal with the rampant bad behavior of multi-billion dollar companies is unpalatable to most.
This is one of those things that might be best solved through policy and law. There probably will be some changes to policy and law to help, eventually. That stuff usually takes a while, and that's always been a problem for those suffering in the interim.
We started with caching but this created a new kind of problems of its own (veterans know what circus of man eating from outside out clowns this create) but client was mad manual refresh is causing "freezes" in the system.
So we ban LLM and problem solved until client starts asking why ChatGPT, Claude, whatever he prefer can't access data and release him/her from pain of using brain