Not sure this is the correct place, but I can't find a "Bug" section in the community.
I believe this to be a bug, I can not find it listed as a limitation. This is for the paid premium connection for SQL Server. If you have a key where one or more column is a text value, if you put a comma as part of the keys text, Powerapps will fail when updating the record. I have not tried creating a new record under the same conditions, only updating records.