Great I'll remove payment:bitcoin and just use currency:XBT and payment:lightning for some of my listings I'm maintaining which are really lightning only.
Currently, payment:XBT will display as on-chain.
We're currently debating the the OSM community on the most appropriate tagging regime: https://community.openstreetmap.org/t/bitcoin-tagging/2302.
I would like to see onchain being explicit using the payment:onchain tag.