It appears that the random intermittent freezes every few minutes where the desktop/apps/pointer is unresponsive for a second or more is not limited to Fedora or Thinkpad.
The reason is likely Intel i915 GPU.
I found a discussion on Reddit that documents a solution in parts spread out over several comments for the complete answer:
https://www.reddit.com/r/thinkpad/comments/rhbf8m/solution_thinkpad_short_freezes_on_gnulinux/