Ok, now I found out. Your Nostr profile (kind:0) has nip05 set to hasky@coinos.io but no lud16 (Lightning Address). Most clients only check lud16/lud06 to determine if you can receive zaps (like Jumble, Yakihonne, Amethyst etc.) so your zap button appears disabled everywhere. You should add lud16: hasky@coinos.io to your profile metadata. Coinos serves both NIP-05 and LNURL on the same address, so it'll just work for everybody once you set it. I've changed NoorNote's LN discovery to fall back to NIP-05, if no lud16 was found. And now it worked.