Strict Transport Security is not set to at least 15552000 seconds
Just discovered this warning in Nextclud Admin area. The problem was actually solved.
I configure my servers with the help of KeyHelp and as you can see in the picture, HSTS is set to 180 days.
Does this message appear again maybe because I switched from PHP 7 to PHP 7.3?
No, its a Webserver setting as far as i remember. I used to put a line somewhere in apache, to config this.
Okay, I found the cause.
I ran the check again on another computer and this message did not appear.
So it seems to be a browser problem. The browser on which the message appears is on a company computer and it seems that the settings of the browser is a bit restrictive.