[Answered ]-When I share the embedded video link that I got from the Vimeo site on my Heroku app, it gives an error

You can try multi steps:

1 – Add this attribute to iframe tag <iframe ...referrerpolicy="strict-origin"></iframe>

2 – change the cookie policy, located under "Shields" > "Cookie Control", to "Allow all Cookies".

3 – Try different browsers to check if this is related to your browser and delete your cookies