Ok i created a clean new forge server and there it works.
Even if i add dynmap and sqlconnector there it works. So dynmap doesn't seem to be the problem.
But removing dynmap and sqlconnector from the old server doesn't help there.
Don't know why this happens only on the old server maybe something went wrong in conversion from 1.18 to 1.19?
I have this problem since a very early forge 1.19 version.
I seems to be a problem with the world files. Just copied only the world files to the new working server and then it has the same problems.
If you know something where i could look to rescue the world that would be nice, if not then iam unlucky ^^