Google console started reporting soft 404 errors for our website lately. We are using NextJS.

For example for this url:

It shows that URL is not on Google.

When I test Live URL:

It shows no errors. When I request indexing yes Google indexes this page. But after some time, It drops from the search results again. I have read all the "Learn more" suggestions. But I could not find a way to fix it.

There is a case study about this, that I will try but not sure if that is the solution. Study

Is it possible because of Next's JS files? But then why I do not see any problem when I live test url?

Is there anyone encounter with the same issue?

Thank you in advance.