On my KDE Neon 20.04 Testing Edition with 5.8.0-31 kernel & dual 1080p+2160p setup, the display scaled down to 1024x768 and only showed it on my 4K monitor (can’t change the resolution from Plasma’s display settings). I tried opening NVIDIA settings and nothing showed up, either. Reverting back to 450 fixed it.
I’ve seen another report on KDE’s bug tracker that Kubuntu 20.10 (which uses Plasma 5.19) is experiencing issues with 455.
nvidia-bug-report.log.gz (103.8 KB)
Here’s the bug report I posted on KDE’s bug tracker.
Operating System: KDE neon Testing Edition
KDE Plasma Version: 5.20.4
KDE Frameworks Version: 5.77.0
Qt Version: 5.15.2
Kernel Version: 5.8.0-31-generic
OS Type: 64-bit
Processors: 4 × Intel® Core™ i5-6500 CPU @ 3.20GHz
Memory: 15.6 GiB of RAM
Graphics Processor: GeForce GTX 1060 6GB/PCIe/SSE2