After more than a decade, BIP 21 has finally been replaced. Existing wallets shouldn't need to change, but this is a great opportunity to check that you pass all the test cases!
Also, if you support lightning check that you support paying to QR codes and URIs of the form bitcoin:?lightning=bolt11 (many do not) and bitcoin:?lno=bolt12offer (most do).
https://github.com/bitcoin/bips/blob/master/bip-0321.mediawiki
