Looking at the required paperwork, I agree with Pocketbase to refuse funding.

If you were already setup as a non-profit entity with 501c3 US taxes (or similar in other locales), this would be straightforward. Or, even if you were a for-profit company taking part with an LLC or other corporate structure. In those cases, you probably already have an accountant or tax advisor to help handle this stuff. For smaller individual level contributors, I can see how the extra paperwork and overhead could create enough of a hassle to make it not worthwhile. Which is sad.

It looks like the author here is from Bulgaria, so who knows what other hassles they would have on their side.

Why? I don't see it as particularly onerous. They are simply complying with their country's KYC requirements. I've gone through worse to accept payments from US citizens with a US corporation. KYC/AML is annoying but its pretty unavoidable unless you want to do crypto.