Blue question marks all over the floor when people spawn in

Yesterday, after spawning in, these question marks appeared. It happens to everyone who spawns in. I didn't change the world or add anything, but they came about regardless. Does anyone know how to fix this? All my mods work fine. This is build 42, a hosted server as well. Any help is greatly appreciated 😃

https://preview.redd.it/ula7ucxvk55h1.png?width=1458&format=png&auto=webp&s=3e90b80183d1b67b7755d403d747c5183c0caa80