Ugh, sorry, no fun! Especially without a good filter. Vouch is an interesting idea, but adoption is still very early and needs more iteration.

One thing to consider, it looks like these are all probably pingbacks, not webmentions per se. Pingbacks tend to be mostly spam, so if you don’t care about them specifically, you could stop them by removing <link rel="pingback" ...> from your HTML. Up to you!