Hi HNRK,
Looking at your past posts, the actual Caddyfile appears to have more settings.
Some of them are left in .json, which seems to be bad.
What I checked was the status of the certificate:
harmoniks. de’s certificate has not been issued recently,
but it was only issued last month and has not been renewed since it has not been 30 days old.
Probably there is something wrong with such a long Caddyfile.
Or you need a mechanism to reset the json settings.
I know the implementation of markdown, but it leaves others to help.