I was about to tear my hair out because I couldn't figure out what was causing this, much appreciated. For further reference for anyone searching like I was, it can also appear in the server's logs as the following:
[Netty Epoll Server IO #4/ERROR] [net.minecraft.network.PacketEncoder/]: Error receiving packet 106
java.lang.NullPointerException: Cannot invoke "net.minecraft.resources.ResourceLocation.toString()" because "p_130086_" is null
This was personally on 1.20.1, and likely is caused by not having the "Survive" mod, or any other similar dependencies of UnionLib while it is still installed. The variable "attribute.name.generic.draw_speed" is getting called when shooting a bow, but isn't pointing to anything causing the NullPointerException in the logs.