Minecraft experts, I’m going crazy here.

My son has an ipad and his friend an Android tablet. They were playing together on our server today (bedrock server running on a VPS) when my son said they were leaving to play on his mates world. When I asked him it was just a local world on his friends tablet. When they finished on that his friend joined my son on my son’s local world on his ipad.

They weren’t on the same network or anything - my kid was at home and his mate at his own house - but it appears they could play on each other’s worlds as ‘friends’. I thought this wasn’t possible.

Is this a new feature? Both are running uptodate bedrock clients on ipad/saming tablet.