Getting disabled right after signup usually means Facebook flagged something about your setup, not just the IP. They look at things like your browser fingerprint, screen size, fonts, WebGL, and even audio context. If you’re creating multiple accounts from the same device, it’s easy for them to connect the dots, even if you switch emails or use a clean proxy.
To avoid that, it's better to create each account in a separate environment. I’d suggest using an antidetect browser (something like GoLogin, Hidemyacc, etc.) combined with residential proxies. That helps make each account look like it’s coming from a different real user. Also take it slow when signing up: no rush, no sudden changes.