java.lang.IllegalArgumentException: Packet too big (is 3180933, should be less than 2097152): net.minecraft.class_2873@572906fe

that should be shown and is normally shown on 1.16.5 (not word-for-word, the above codeblock is from logs instead)

this happens rarely but like when loading items with too much nbt this will happen (e.g. creative item hotbar) it will happen for example. just a small small bug where when I am kicked it does not say the error on the kick message and the kick message is left empty.