this is not a "bug", this is a natural product of messages being gossiped out of order which is how gossip works.
This is a warning, not an error... if you see it repeatedly only then you should be worried
From: "Faisal" <mfaisaltariq@...>
Date: 03/24/2020 09:04 PM
Subject: [EXTERNAL] Re: [Hyperledger Fabric] Signature Byte Isn't Valid Warning On Gossip After Addition of a New Org #hyperledger-fabric #configtxgen #raft
Sent by: fabric@...
Is this fixed in the 1.4.4 version LTS as we plan to upgrade the network in the coming weeks?