@SlicedBlock thanks, it seems to be a duplicate. I don't know how to delete these though
Added pictures, still happens in 20w20a. They always get ejected into the block the minecart is on, doesn't matter if there's a rail below or not. I wish they would stay in the cart or at the same level as it, so they don't potentially fall through the floor
I had the same thing happen to me, filled a bucket with lava, entered a nether portal and the lava is gone