What does _0_4_ mean in ghidra?
It is being used when there's a mismatch between type sizes in the decompiled code and Ghidra cannot show you that the whole variable is being modified.
PUCHAR - since it is a pointer and this is (probably) 64-bit is 8 bytes. But analyzing the disassembly Ghidra sees that only 4 bytes are being set to 0 in this line (for example a 32 bit register is used).
One of the fix you can apply is by correcting the type of
local_res8 (CTRL+L) but it might be the case that the type is ok, and in fact only lower 32-bits are being set..