As I already stated on the LinkedIn post: I doubt that the ad restriction is enforceable (in Germany) since there are enough rulings about §23 Abs. 1 Nr. 3 MarkenG that allow mentioning a brand without consent in order to specify your own goods or services.
I have concerns that the bad faith actors still advertise as they want and you cannot enforce your rules… and the small good faith actors are scared away now.
Have you considered the case where someone is looking for a developer skilled in TYPO3? If they pay to post a job ad on an external platform, technically this violates the rules. Expecting everyone to request permission just to mention it in a job description — simply because they require experience with it — is, well… let’s just say it’s not very realistic.
It is also for editors btw. It means, that a university is not allowed - without written permission - to post a job ad for an editor with TYPO3 experience in a typical paid platform.
I think you should consider to extend the “fair use” rules allowing job ads, because that is essential for the community to be able to grow.