Link preview metadata abilities are only available when posting to Facebook only and the domain must be verified
To ensure link preview metadata works correctly, you need to do the following:
1. Your Facebook Page must be managed under Facebook Business Manager
2. You have verified your domain
3. You have assigned the domain to the pages you will be posting to
If you believe you have done these already you can check this under:
Business Settings > Band Safety > Domains
If you aren't the owner of the domain, you can ask the owner to verify it on their own Facebook Business Manager and to make you a "Partner" by asking them to generate a link for you.
How to allow another Facebook user (Partner) to use your domain to be able to link previews metadata
Go to Business Settings > Brand Safety > Domains > Assign Partner > Select Domain admin > Copy
Once you receive the link and you accept the invitation, you will be able to edit the link preview metadata for that domain.