According to this page
https://www.elastic.co/guide/en/kibana/7.x/autorefresh.html
and the last sentence
if auto refresh is not enabled, click Refresh to manually refresh the search results.
It seems like there is a way to disable auto refresh on any dashboard somewhere.
I searched a lot but unfortunately I did not find anything on how to do this.
Reason is our clients open the dashboards, configure them to the minimum refresh rate (every 5 seconds) and leave it open all the time (even over night) which causes a constant load on the server.