Found while playing on my 1.14.1 server. while in the nether, exiting a minecart with a button above it and exiting the minecart while stationairy causes the players character to fall through the block beneath the minecart as if it wasnt there. Have attached screenshots for reference, confirmed it can be replicated everytime.

How to replicate:
there has to be a FULL BLOCK ceiling over top of the rails, having a slab above it causes the player to exit normally

you can glitch through any block using this method, including bedrock.

http://prntscr.com/no3b70

Jira is not letting me attach any images for some reason so here's a link on how to replicate this bug.