A Wordpress plugin to obscure content to discourage AI ingestion.
This is not fool-proof, but will add a roadblock to ML use of the data.
It inserts zero-width whitespace characters that are effectively invisible to humans in the middle of words, while also replacing visible whitespace with non-standard, but valid, whitespace characters.
This somewhat blurs the boundary of what's a word or not, and should work until AI companies add a clean-up process to compensate for it. But until that's added, it may prevent your content from being trivially used.
In the end, preventing your content from being used without consent or payment requires a social and/or legal solution, not a technological one. But until then, give this a try!