I’ve had it shut off, as I got too many stale pages from apps that really need to serve all pages dynamically, so I guess Varnish is simply not for me.
Getting rid of it wasn’t easy though. After deactivating it via the console everywhere (so logically speaking it was gone), Cloudways support still needed to perform 3 further actions before it was gone for good, and the last step was taken yesterday, so I’m still evaluating whether it now works fine.
One of the problems shutting it down was that autohealing kicked in trying to restart the Varnish process every minute, causing lots of activity in that aspect of monitoring, possibly shadowing real autohealing attempts. After that pages sometimes caused Guru Meditation that again required manual intervention on support’s part. Not to mention they adjusted Nginx settings to make it perform better.
So be aware that after trying out Varnish and you want it deactivated you might need to make non-intuititive cleanup and post a lot of tickets, and meanwhile have partial downtime for days.