One example: https://pantheon.corp.google.com/errors/COS7j-Kzpv_J1AE?time=P30D&project=findit-for-me

Error message:
TypeError
Incorrect padding
b64decode
Request
GET findit-for-me.appspot.com/flake/occurrences?key=%5B%5Bflake.flake_urlsafe_key%5D%5D
Status
404
HTTP Referrer
https://findit-for-me.appspot.com/
User agent
Mozilla/5.0 (Linux; TO STOP THIS SECURITY SCAN go/scan; GoogleSecurityScanner); AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.15 Safari/537.36 (scan 6099980396822528, run 5824676368252928 GoogleSecurityScanner)

These kind of errors should not be reported.

A previous fix: https://chromium-review.googlesource.com/c/infra/infra/+/890243