Trials flood when in water caves.

When a trial ruins spawns in a water cave then the slabs turn into waterlogged slabs, Flooding the structure.
Make a world with the seed -2683458371323364231 in 23w45a and use 
/execute in minecraft:overworld run tp @s 2593.59 0.60 2363.96 3018.73 23.39 to teleport to the place. Or just find a water cave with a trial dungeons in it.