Finland has solved the problem of AI use in literature, the same way it solves every problem: through unionization.
You literally are not a writer in Finland if you're not part of the Union of Finnish Writers. To be considered eligible, you must have published at least two independently authored literary works in Finnish, and be "writerly" at the "artistic and professional level of your output", in other words, to have been received well by the critics and not to have misbehaved too badly at the parties.
Just weeks ago, the union issued a decree stating that in the face of the proliferating use of AI in writing and related scandals abroad, no member is allowed to write without supervision: writing may only be done in the presence of at least two senior union members, and only in longhand.
The policy seems to be a success in that there have been no local scandals so far, but writer responses to the rule have been varied: some say that they can't live like this, others that it's a great perk to get live feedback from senior colleagues they admire, even if it's in the form of various grunts, groans or smiles as they watch over their shoulders.