Looks like a fixed bug regressed recently.

What steps will reproduce the problem?
(1) Launch chrome, open NTP and then toggle browser to Fullscreen mode.
(2) Hover mouse over tab strip and observe.

Actual: Unwanted moment is seen after hovering mouse over tab strip.
Expected: No such a moment should seen.

Details can be found at https://bugs.chromium.org/p/chromium/issues/detail?id=864931#c10