Have you ever had this issue on your website with Firefox, where your Adsense wouldn’t load at all after everything you have tried? You came to a right place.
I am glad that my browser is Firefox, which helped me to notice this issue faster. In Chrome, there is just some blank spaces.
I did some searches and there is no information why this happen.
After a bit of investigation, the culprit turned out was an HTTP header
In my case,
Cross-Origin-Embedder-Policy caused the issue. You can read more info about the header from here.
My easy solution is to remove the header. If for some reason you cannot disable it, change the value from