Can a wildcard certificate from one domain work for another on the same server?

Question

linux

Hello. I am not very competent in the matter, so I want to understand the following:
If there are two different virtual hosts with different domains on the same server, but both are configured with a wildcard ssl certificate of the first domain, then the second domain should not work via https without swearing at the certificate, right?
The second domain is not a subdomain of the first, the names and even domain zones are different.
If the site does not swear and the green icon in the browser is on, then this is mitm? And if not swears, but yellow?
Both domains work through different cloudflare accounts, can the certificate work without mitm in this case?

Answer 1

Cloudflare signs everything with its certificate, what you have configured on the server is not very important at all. Cloudflare itself works on a principle similar to mitm, it receives data from you over a secure or insecure channel and sends information signed by its certificate to the end user.
The certificate will work as it is actually issued and signed. There are multi-domain certificates, there are for one domain, there is a wild card, etc. Self-signed junk is another story altogether.