The Edit votes page does not write voting changes if too many made at once

[MichaelNMaggs]

In a yes/no round, after making large numbers of changes to previous votes and hitting the Save Changes button, nothing happens. The Save Changes button still records the same number and the changes are not to be written to disk. Refreshing the page in Firefox causes all the edits to be lost.

Happens consistently but only when large numbers of voting changes have been made (over 100 changes definitely causes the issue)

MacOS 11.4 with Firefox 89.0.2