I would like to up this, having the same issue, random spikes of around 50-60 ms.
Using linux beta 5.6. This issue has been reported multiple times though, but could never be reproduced. I can’t reproduce it on my windows machine either, nor does it happen in empty projects (most of my projects for that matter).
I’m using amd drivers, my project only contains a camera gameobject with some monobehaviours on it, everything else is done via the Graphics API. So tips regarding the UI Canvas don’t help.