Steps to replicate:

• Be in a bed while other people are on server and not in a bed
• Start typing in chat

Unexpected behavior: Within a few words (averaging 15-20 characters), you get disconnected from the server with an error "flying is not supported on this server"

Replication has been pretty consistent for me, but I haven't trial & errored it enough to definitively say 100% reproduction.

Server info: Minecraft 1.14 Pre-Release 2 (1.14 Pre-Release 2/vanilla/snapshot)

Client CPU: Intel Core i7-6700K

Display: GeForce GTX 1070 PCIe running 4.6.0 NVIDIA 417.35 drivers