Histogram suggests this is not a huge problem.

For the histogram Suggestions.FetchResponseCode in the last 28 days, there were:
 - 3,364,349,734 total samples on Android and Windows stable
 - 40,252 401 responses
which is:
.001% of responses.

On Android, out of 47.5M users reporting FetchResponseCode, only 37 reported 401 responses.  It does seem that those 37 tended to have multiple responses rejected, as there were 252 individual reports.

Lowering priority accordingly.