I don’t know what the problem with the cursor is, but for the brightness… I suspect the game uses sRGB gamma. I hate games that use that, it’s incompatible with flip model. I have developed an override for that, but then gamma no longer works correctly. There’s no good solution, the developer should simply not use sRGB.
As for all that silliness about specific rates to get lower input latency, I don’t believe any of that for a second. Special K has a new low latency limiter mode, it doesn’t work by fudging with numbers, it actually works by changing when the finished frame is presented for final output.
I would encourage trying SK’s new low-latency limiter settings instead of following guides that tell you there are magic numbers even if they were written by pretty respectable websites