relative URL (/subpage/) = invalid data

Hello, on a WP 7.0 and PHP 8.5, this appears after activating the plugin 1.9.7:

i think that it is generally recommended not to use absolute URLs on pages: https://mydomain.com/subpage
but rather relative: /subpage/ so when the site domain/address changes, then links are not broken.

When i have tried to set relative URL at /wp-admin/tools.php?page=tso-link-inspector&filter=broken&orderby=link_url&order=asc then it told me “Invalid data.”, but full/absolute URL worked.

Maybe Link Inspector should accept any address or better any valid addresses, like ones starting:
./
../
/

maybe subpage.php can be considered invalid, even it should work to link to a page on same directory level.