I'm facing an odd bug.
I've a multi-line text metafield linked to my product page as a dynamic source in a richtext field (the only one that supports it).
If I include some simple HTML tag in the metafield value in the product, they are converted as text and shown in the page.
If I add to the richtext some other text and use the interface to make it italic it's displayed correctly. I think that is a bug because there is no way to include some formatting in a metafield multi-line text using the customizer.
I've tried to use a single-line text metafield as a dynamic source of a text field and putted some HTML tags in it and it works like a charm, in a field that is supposed to strip that.
I've found a workaround: In the block I print the metafield directly via liquid referencing it with product.metafields.my_meta.meta_name where my_meta and meta_name are the ones I've chosen. In that way the HTML works fine.
If you're a bit more advanced with liquid you could pass the "meta_name" value in the block settings as string and access it in the object with product.metafields.my_meta[block.settings.meta_name] to keep it dynamic and controllable in the customizer.