This is the obvious solution to watermarking text in a way that isn't easily removed by a dumb tool.

The output quality will likely suffer as stated in the article although this can be mitigated to an extent by only enabling it on more irrelevant filler text while leaving the more functional sections untouched.

The solution using Unicode tricks amounts to malicious compliance as only the most unsophisticated users are going to fail to remove the AI watermarks when trying to pass off AI slop as their own prose.

The real solution here is not having stupid EU–tier laws in the first place.