I am facing the same issue reported here:

forums.limesurvey.org/forum/installation...pt-on-topic-creation
forums.limesurvey.org/forum/installation...pt-on-topic-creation

I would really like to respond to the kind people who have written back to me, but all I can do is click "Thank you". I wrote to customer services and got the following suggestion:

1. Refresh the page and try again with a new anti-spam test.
2. Check JavaScript and cookies:
   – Make sure JavaScript is enabled and that cookies are allowed for forums.limesurvey.org.
   – Temporarily disable your ad blocker (AdBlock, uBlock, etc.).
3. Try another browser or private mode.
4. Test with another internet connection.

However, the issue remains. I keep failing the spam check in every browser and across both Windows and even Linux, through both clearnet and VPN.
I'm left without the ability to reply due to this.

I am posting here in the hopes this can be addressed as I have no other recourse. Thanks for your consideration.

Unfortunately we as moderators have no control over this. This would be really something that the Limesurvey GmbH support would have to solve, which I assume is who you contacted.

Strangely enough, you can post here, opening a new topic, but not on old topics?

Strangely enough, you can post here, opening a new topic, but not on old topics

That's correct, yep. That's been the case with my 3 topics so far.

Strangely, I am no longer subject to spam checks since I wrote this. The box to do a calculation is gone everywhere. Maybe my pleas landed, or perhaps I've just made enough topics at this point that marked me out as a non-spammer.

maybe there is something in place that when a moderator interacts with you, you are considered "human", who knows. all this is handled by the Limesurvey GmbH, we as moderators have no insights on these internal workings of the forum and the spam check.
But I have seen that you were able to post again. Great!