quoting directly from the browser automation guide which you should've read and consumed before being a developer:
Using a Write stage to write to an HTML element such as a text field
does not always work properly. For example, you might try writing to a
username field, only to see a message appear on the web site saying
something like “Please enter a username”, even though you can see that
the value has been correctly written to the field. This can happen
because the data validation functions used by the web form might be
expecting keystrokes, and the write stage has “fooled” it. To get
around this, you will need to use a Navigate stage to call the Send
Keys Action instead of using a Write stage. Some websites have maximum
character limits imposed on some text fields. Using a Write stage can
sometimes fool the website into allowing too many characters into the
field, because the Write stage “sets” the field value rather than
keying characters into it. This is important to bear in mind because
if a field has been filled with more characters than the website would
usually allow, the website could produce an error when you try to
submit or post the data.
to get around this go ahead and use sendkeys, those are likely the best option to push past this validation tool issue on the website.