This bug has been driving me absolutely nuts for about 6 months. I was sure it was my router or my ISP (who would suspect a brand new $2500 macbook pro??). Spent countless hours trying to troubleshoot a nonexistent issue with those. I finally dug out my old 2014 macbook pro and the connection is absolutely perfect. The ping is an extremely consistent 20-30ms. On my new mac running monterey, every 30-60 secons or so, the ping will spike up to 1000ms+ or completely drop packets for ~2-3 seconds. Apple has built up a tremendous loyalty from me over the years, but these are the sorts of issues that will very quickly erode all of that.