The scheme site property might not be taken into account when the SXA link provider (localizedProvider) is used.
This issue affects SXA 1.7.1 - 9.3.0 versions.
To resolve the issue, download and install the patch compatible with the affected product version found on this page:
https://github.com/SitecoreSupport/Sitecore.Support.318160/releases.
To get a solution for other releases, contact Sitecore Support.