I forgot to write if you have a key with, say, 4 or no matter how much unknown characters in various places - then the code is like this
unk1 = ''.join(secrets.choice(alphabet) for i in range(1))
unk2 = ''.join(secrets.choice(alphabet) for i in range(1))
unk3 = ''.join(secrets.choice(alphabet) for i in range(1))
unk4 = ''.join(secrets.choice(alphabet) for i in range(1))
unkX......................................................
WIF=f"5J{unk1}5bCRZhi{unk2}5sEGMpmc{unk3}ZdpAhmWLRfMnutGn{unk4}"