Because it is the hardest one to answer

We tested zaps on this note… we made six attempts to⚡zap this note, at xanthin@nostrgo.com, over a period of about 2 hours. In each case, we found that your lightning address server did not respond correctly. (The failure point was when we did a GET request to your specified callback URL: https://lnbits.nieva.com/lnurlp/api/v1/lnurl/cb/g2Nf5R ). Your server did not produce an invoice, thus the zap failed. The error we got was "Amount 1000 is smaller than minimum 250000.0.". You might want to look into using a cloud-based Lightning node which is optimized for Nostr zaps, to get your zaps working.