I also am seeing this problem on a Yacy peer running on Windows. If you look at your server log, what do you see?
/ViewLog_p.html
If you search for OBSERVER you might find a clue. In my log, I found this:
W 2025/05/20 05:59:34 SWITCHBOARD Crawl job ‘50_localcrawl’ is paused: resource observer: too high disk usage, EXHAUSTED
I 2025/05/20 05:59:34 RESOURCE OBSERVER pausing local crawls
W 2025/05/20 05:59:34 RESOURCE OBSERVER Volume C:\Users\User\YaCy\DATA: used space (27312 MB) is too high (> -1 MB)
Notice it says “used space (27312 MB) is too high (> -1 MB)”. I hoped that a setting of “-1” would tell Yacy the disk limit should be removed completely for unlimited use, but that did not work.
So, I went to /Performance_p.html and changed some values.