Hours (Timesheets) – "Add row" button should be deactivated for Dates preceding Employment Start date

Employment date for this user is 29/04. Clicking on “Add row” still allows for adding a new row, however it gets greyed out right after. When refreshing the page, the row is not there.

Should the “+ Add row” button be greyed out all together for dates preceding employment start date?

[View after clicking “Add row”] – if I refresh page, entry won’t be there