Is this shounen ai or yaoi?

it was probably shounen ai before, when did it change

It is never smutty and doesn't have a lot of romance elements it's more action BL really. This BL is its own genre lol _ (the sex is implied not explicit so it's more to the Shounen Ai side?) But okay it won't be a good read for someone who is into plain Shounen and pure action, and it's better to tag it yaoi because Shounen ai fans would be deceived otherwise. So I think it's good to have put the double tag Shounen + Yaoi :-)