So I was testing the world conversion of Bedrock Switch and I saw that one of my blocks in my survival world had changed to tile.info_update.name. So I went back to Legacy, went to see what block it was and I saw that it was a cauldron with 2 high water in it. So I created a world with three cauldrons in it: one with 3 high water, one with 2 high water and one with one high water. Upon conversion, the cauldron with 2 high water had changed to the tile.info_update.name block as with my survival world.
Additional information is supplied on MCPE-33932.