https://chromium-review.googlesource.com/c/520946 originally had these following footers generated by Gerrit:

No-Presubmit: true
No-Tree-Checks: true
No-Try: true

Despite these CQ has run presubmit. Changing footers to

NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

has helped.