How to force telegram to update link preview?
You may add /?v=n at the end of URL when sharing the link, where n can be any number and should increase after an update.
Go to @webpagebot and send the link (up to 10) you want to update. Automatically will scan your site and generate the new image thumbnail, site name and description.
Remember to have og prefix in your html tag as: <html prefix="og: http://ogp.me/ns#"> or telegram bot will not update the graph cache.
via telegramgeeks
Sending the pure link to @webpagebot would not work so I used
<meta property="og:url" content="https://mylink.com" />
and it worked.