Hi there,
Many thanks for your reply.
I just downgraded to WP 6.0.1. and the problem is still there. (so my early claim that the problem had something to do with the WP version is false). I even unchecked all checkboxes under “Purge Policy: Page Cache”, removed the path to the sitemap and set purge limit to 1.
Even now, when I open a post in the WP editor and hit “Save”, all page cache is flushed.. This should not happen, right?
I have another website which runs the exact same WP version and W3 total cache version, but there this problem is not present.
Update: I think I found the solution, there was a difference between the 2 websites.
I added “add_filter( ‘rank_math/sitemap/enable_caching’, ‘__return_false’);” to the functions, and now there the problem seems to be gone.
This looks like a rankmath conflict with W3 Total cache.
Case can be closed, thanks again for your time!