The 104.x address is Cloudflare's proxy. Your A record has the orange cloud on, so the world sees Cloudflare, not Lovable's IP, and Lovable's check keeps failing.
Cloudflare → DNS → click the orange cloud on the @ and www A records so it turns grey ("DNS only"). Then in Lovable hit retry. Usually verifies within minutes and it issues the SSL certificate itself.
You can try switching the proxy back on after it's live but honestly there's little reason to, and it can break certificate renewal.