Possibly, but we don’t (can’t) know. You can’t just make that kind of statement by counting the number of users who register an account here and post in this thread. It’s likely that users in a mobile or otherwise noisy environment have it and never even notice it, and so they’re fine anyway. Or that some notice but don’t mind it enough to find this one thread on the internet to complain about it. It’s also a condition that appears to worsen over time, so someone unboxing and saying it doesn’t have any noise doesn’t necessarily mean it will never develop any noise. Neither of us know for that matter exactly how many units are in users’ hands and how many support tickets are opened up with Uniden about it.
Please stopping with the yelling. Yes, if you do something that causes damage, that damage will not be required to be covered under warranty. But to be clear, it’s up to them to prove that the thing you did caused the problem. If you buy new wheels to replace the OEM ones and your transmission goes out, they can’t claim that you modified the vehicle and therefore all bets are off. If you put in a custom exhaust and your A/C stops working, they’d have to show that somehow the exhaust caused the problem. If you tint your windows and the shifter linkage breaks, etc, etc, etc.
In this case, if you go about modifying the scanner, and that modification causes damage, they’re not liable for fixing it for you for free. For example, maybe you add a ground strap, but that ground strap touched some components and shorts something out. Not covered under warranty. If you go and replace a capacitor or remove a resister on the board, and that causes a problem, not covered under warranty. If you open up the case and write your name in sharpie inside the case, they can’t claim the warranty is forfeit. There are lots of things you can do that wouldn’t invalidate the warranty, as long as whatever you did wasn’t the cause of the issue.
I don’t think you’re on the right track. You’d have to modify the fundamental function of the receiver and its components in such a way that it creates new emissions or something along those lines. The mitigation part from Uniden modifies the SDS200 and posed no risk of somehow running afoul of the FCC. Neither does a soldered/bolted ground strap, for that matter.