Google Site doesn't work with Proxy enabled

[mondoeitalia]

What is the name of the domain?

mondoe.net

What is the error number?

1016

What is the error message?

DNS Error 1016

What is the issue you’re encountering

Google Site doesn’t work with Proxy enabled

What feature, service or problem is this related to?

DNS records

What are the steps to reproduce the issue?

I connected my domain mondoe.net with my Google Website, so I enabled the Proxy and create a Page Rule so the URL will be without www, but I find out that the Website works only if the CNAME is Only DNS and not with Proxy enabled.
So is there a way to make a www to none www with Only DNS or a way to fix this problem in the first place?
General Information: My SSL/TLS is Full (Strict) and my Page Rule is on the screenshot linked to this post.

Screenshot of the error

[sjr]

Your redirect is from www to the apex domain, but www isn’t proxied (it’s a CNAME to Google) and there isn’t a DNS record for the apex domain…
https://cf.sjr.org.uk/tools/check?e88b305d7a32482aa60ebf1b35d1a219#dns

First set your apex domain to a DNS only CNAME to Google, the same as www is now. Check that works so you know Google is answering for your apex domain. Make sure this works before continuing. If it does not work, you need to add your apex domain as a custom domain to Google.

When that works, you can change the www CNAME record to proxied AAAA 100::, then your redirect will work.