I have a Sony KD-49X7052 with strong fibre broadband (130Mbps) and newly installed TV aerial cable. Sony TV picked up all the channels with 98% strength. I have the latest firmware as of 01/07/2021

I can watch any SD channels just fine. HD channels just froze, distorted and crackly noises. 

Checked with Google that the HD issue is down to the firmware. Is that true? Sony handles HD badly?

Please help. Thank you