Like the title says, the merged mode doesn’t end when swapping the 3rd slot spec to something else, like soulbeast -> druid or -> beastmastery. The character can’t summon pets and retains the pet type stat boost (like condidmg and precision from “deadly” pet) until 3rd slot is set back to soulbeast and merge manually ended.
Kitty recorded a video to show how the bug behaves: https://youtu.be/en915Y7UMsI
That could be possibly abused, so it prolly better be fixed well before launch.