Apparently solved it… After remove my domain from Cloudflare and starts the migration to the SSL tool from Infinity, my site goes down. I didn’t know it was a problem on the server and I restarted the process.
Halfway through, I found out about the server problems (yesterday), so, I went to sleep, woke up today and started trying through Cloudflare, now my subdomain is working over SSL too.
In the process, I discovered how to use subdomains in the SSL tool provided by Infinity, it was simpler than I imagined, and if I need it in the future, I will already know what to do.