My subdomain website suddenly is redirecting to main domain "sometimes"

I have a website in a subdomain that suddenly started to point to the website in the main domain.

I tried several redirect inspectors online and they showed this behaviour as 301 permanent redirect (that I didn’t do).

I checked my htacess files at the domain/subdomain also the redirections one cpanel and cloudflare and nothing seems to be forcing this redirection.

the behaviour also is really strange: when I type the url of my subdomain in several browsers it sends me to the main domain, but when I google my subdomain or navigate through any link it shows the correct content of the subdomain.

Also when I copy/paste the url of the subdomain it takes me to the correct content, but when I type the url it sends me to the main domain.

Any insights on this problem?