When providing an og:image you should explicitly provide an image style. This is not clear from the description below the og:image field, and it's currently not possible to provide an image style for a media field using the token browser.
Enable the Open Graph submodule and go to /admin/config/search/metatag/node. Locate the field by searching (CTRL+F) for "The URL of an image which".
Change
The URL of an image which should represent the content. The image must be at least 200 x 200 pixels in size; 600 x 316 pixels is a recommended minimum size, and for best results use an image least 1200 x 630 pixels in size. Supports PNG, JPEG and GIF formats. Should not be used if og:image:url is used. Note: if multiple images are added many services (e.g. Facebook) will default to the largest image, not specifically the first one. Multiple values may be used, separated by `,`. Note: Tokens that return multiple values will be handled automatically. This will be able to extract the URL from an image field if the field is configured properly.
to
The URL of an image. You can paste in any image url you like or use tokens like [node:field_media:entity:field_media_image:wide:url] and/or [node:field_image:0:wide]. With both media fields and image fields, you need to provide an @image_style (in the above example wide).
Multiple values may be used, separated by commas. Many services will default to the largest image, not the first one listed.
For best results use an image least 1200 x 630 pixels in size. @Format: JPG, PNG, WEBP, GIF.
Tokens that return multiple values will be handled automatically.
You cannot rely on the token browser to suggest all useful tokens.
Should not be used if og:image:url is used.
@image_style is at /admin/config/media/image-styles
@Format is https://joost.blog/use-avif-webp-share-images/
It is a small increase in number of words (from 117 to 121), but a huge increase in usability.
Rewrite the text.
You could also try to make the token browser behave better around media fields, but that's a way more complicated and time-consuming task - and rather less useful IRL, to be honest.
Active
2.1
User interface
Modified description for og:image field as per the suggestions. This needs to be reviewed.
Before:
Updated description: