To get the iframe I did:
GET
https://vimeo.com/api/oembed.json?url=https://vimeo.com/508864124/fcbbcc92fa
So I got
{"type":"video","version":"1.0","provider_name":"Vimeo","provider_url":"https:\/\/vimeo.com\/","html":"<iframe src=\"https:\/\/player.vimeo.com\/video\/508864124?h=fcbbcc92fa&app_id=122963\" width=\"426\" height=\"240\" frameborder=\"0\" allow=\"autoplay; fullscreen; picture-in-picture\" allowfullscreen><\/iframe>","width":426,"height":240,"domain_status_code":403,"video_id":508864124,"uri":"\/videos\/508864124:fcbbcc92fa"}
UTF-8 Decoded: for the iframe
<iframe src="https://player.vimeo.com/video/508864124?h=fcbbcc92fa&app_id=122963" width="426" height="240" frameborder="0" allow="autoplay; fullscreen; picture-in-picture" allowfullscreen></iframe>
The iframe itself
Edit/Update:
I have submitted a PR to fix, I think the problem was with regex pattern. It didn’t captured vimeo correcly when its not the standard type. Thus I changed the regex pattern accordingly.