Unable to include regex patterns in site settings config

Summary:

We are trying to upload a site settings widget, which has an input field, which should ideally contain semicolon separated list of email values.

For ex "support@somedomain.com;help@otherdomain.com".

Content (required):

For validating the entries we tried to use the pattern attribute to specify the regex, but it seems to be not working as expected, because no matter what values we enter it always shows the value as invalid. We are not sure why this is happening as we are able to get the expected validation when we are applying the same regex in normal js.