Question about ACS Income Threshold Cut-offs (B19080)

I've noticed that the ACS upper limit figures for different quintiles in detailed table B19080 seem to be cut-off around $250,000 for the most recent year (2019).  This is true for tracts, block groups, and ZCTA in the 5-year Census estimates.

I went ahead and looked into the annotation information (, but in this case the documentation there doesn't seem to be relevant for the $250,000 cutoff.

Does anyone happen to know where one could find documentation for this issue?  I'm trying to find a Census publication or something similar that would have the justification.  Thanks!