I have been going through old photos and when the previews are generated some of them are corrupted with banding and blocks of colors. It does not happen on my new files. The old files are from Canon 7D Mark II. I assume it is some kind of hardware like memory or hard drives. I am using external hard drives and copied the files from an older drive to a newer drive and it still happened.
Lightroom Classic version: 10.1.1 [ 202101041610-8c69aa4e ] License: Creative Cloud Language setting: en Operating system: Windows 10 - Business Edition Version: 10.0.19042 Application architecture: x64 System architecture: x64 Logical processor count: 8 Processor speed: 3.4 GHz SqLite Version: 3.30.1 Built-in memory: 16286.7 MB Real memory available to Lightroom: 16286.7 MB Real memory used by Lightroom: 2063.6 MB (12.6%) Virtual memory used by Lightroom: 11314.0 MB GDI objects count: 975 USER objects count: 2359 Process handles count: 3156 Memory cache size: 1135.0MB Internal Camera Raw version: 13.1 [ 658 ] Maximum thread count used by Camera Raw: 5 Camera Raw SIMD optimization: SSE2,AVX,AVX2 Camera Raw virtual memory: 835MB / 8143MB (10%) Camera Raw real memory: 836MB / 16286MB (5%) System DPI setting: 96 DPI Desktop composition enabled: Yes Displays: 1) 1440x900, 2) 1920x1080 Input types: Multitouch: No, Integrated touch: No, Integrated pen: No, External touch: No, External pen: No, Keyboard: No
Graphics Processor Info: DirectX: NVIDIA GeForce GTX 750 Ti (184.108.40.20638)