Amp Frequently Disappears in Google

Hi, I have a site where I use Wordpress, I created HTML AMP on it, but although my codes are correct, AMP frequently disconnects, meaning it redirects to my main site on mobile, not to AMP.

And this happens to me almost every day, and as a result, I don’t get any errors etc.
Sometimes it happens for 3-4 days without any problems, then it goes back to the main site, not AMP.

There are no errors in the codes of my AMP site, I test it and I have a problem-free page. https://search.google.com/test/amp → I test from here too, there is no error in AMP.
There is no error. There is no problem in the AMP section in Google WM Tools. It seems like they do not see AMP if they delete the AMP code.
I’ve done a lot of research, but I still haven’t found a solution. It seems like a chronic problem.
I use this code in the header for AMP on my site:

< link rel=“amphtml” href=“ampsite”>
< link rel=“canonical” href=“mainsite” />

In AMP, I use this code:
< link rel=“canonical” href=“mainsite”>

I did not turn on the Real AMP feature, will it be solved if I enable it?
What can I do in such a problem, thank you.

Is there no solution?