I think for zaps to work, as per NIP-57 the zap recipient LNURL service should have a zapper & support Nostr. Only some providers like WoS & Alby support that. Maybe if you change to your WoS LNURL in your Nostr profile, it will work
(Replying basis NIP not experience)
I think this is it.
https://github.com/btcpayserver/btcpayserver/discussions/4642
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I got to know thanks to
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