Flags should either allow longer notes or generate a real error to display to the end user.
Are you able to replicate the issue here? (I am not).
It does not occur here.
It looks like there's a maximum number of characters that a Flag can take.
I have some shorter Flag notes and they seem to work fine when edited.
Oh, nice work. We should either give you an error or remove the restriction. Thanks for the report!
Closed by commit rPf239d81c1cf8.