How to verify that Googlebot can access the URL of a video thumbnail?

Question

I need to check if Googlebot can see my image thumbnails. When I use the URL Inspection Tool, Google cannot see my images in the page. In the rendered screen shot, it displays a black box instead of thumbnails.

Also my thumbnails dropped in SERP.

This is a sample URL:

https://tamasha.com/v/7xGLB

And this is my thumbnail:

https://s-v2.tamasha.com/statics/images/posters/b9/78/7xGLB_b978d6931ce8020a940b3bffd3eeb1e2e7b76bb4_2094x1185.jpg?w=800

I need to check if Googlebot has access to the above URLs.

Note that robots.txt is OK and I checked the verifying Googlebbot page but it doesn't seem to be helpful for this situation.