I was setting up some command blocks for a map i'm trying to make for a lan, when I tried it I realized i messed up the coords and ended up inside the block but what confused me the most is that when in survival i was suffocating even though the block that my head was at was air, that's when i turned on hit boxes and saw this glitch.
Steps to recreate:
1. Set up some command blocks or type a /tp command(doesn't really matter how you teleport the player)
2. start Gliding with an elytra.
3. either use the /tp command or meet the requirements for your teleportation command blocks.
This can mess up some pvp stuff cause the player is literally invincible if inside a glass block.