Importing a profile recorded with Chrome Canary (v90) triggers this error check code:
https://github.com/facebook/react/blob/6c526c5153bc350d2a62c7dcbc698be77d3f2439/packages/react-devtools-scheduling-profiler/src/import-worker/preprocessData.js#L371-L378

Here's one such example event:

{
  "args": {},
  "cat": "blink.user_timing",
  "name": "requestStart",
  "ph": "I",
  "pid": 64032,
  "s": "t",
  "tid": 775,
  "ts": 25788659448
}

Looks like there's at least one new type, "I", which I assume will eventually affect Chrome stable (currently v88).