If you're homelab'ing then you should be using private IPs to host your services anyway. Don't put them on a public IP unless you absolutely have to (eg port 25 for mail).

Use your internal DNS server (eg your routers) for DNS entries for each service. Or if you wish you can put them in public DNS also. Eg. gitlab.myhome.com A 192.168.33.11

You can then access your services over an always-on VPN like wireguard when you're away from home.

Then it doesn't matter if anyone knows what subdomains you have, they can't access them anyway.