I believe I managed to fix my custom NIP-05 for real this time.

I offer a kind acknowledgement to nostr:npub16jzr7npgp2a684pasnkhjf9j2e7hc9n0teefskulqmf42cqmt4uqwszk52 for making this neat guide:

https://orangepill.dev/nostr-guides/guide-to-verify-nostr-profile-nip05-identifier-with-your-domain/

and to nostr:npub1aeh2zw4elewy5682lxc6xnlqzjnxksq303gwu2npfaxd49vmde6qcq4nwx for bringing it to my attention.