Tbh I'd rather compare performance and quality without any upscaling. It's fun to upscale obviously since you're giving some life to older hardware, but it's essentially cheating and it introduces latency which is never really measured. Also as we've seen, the upscaling is mostly tied to software which can change over time, so it shouldn't really be taken into account for comparing GPUs.
What are the old geforce owner using now? AMD's FSR probably.
Can you tell me more about this? First time I hear about upscaling without FSR or DLSS. I don't mean anti-aliasing or linear scaling.