CRT and input lag

[Sandy]

I'm a foreigner and stumbled upon this forum. I used a translator. Sorry.
I have been playing Cs1.6, a very old game, for 20 years. I only learned about input lag in the last year... By chance, I used his CRT monitor to play Cs1.6 at a friend's place. CRT works at 120Hz I experienced what true 0 lag was and I was devastated!!! I realized I had spent 20 years doing this wrong before! I never even suspected the monitor would be the main problem (damn) in years I replaced Countless mice couldn't solve the problem until I used a CRT. Now I realize that the problem lies with the monitor. My gaming score KD increased from 0.98 to 2.2.

I have 3 questions 1. Does the higher the refresh rate, the harder it is to reduce input lag? Why?

2. Recently I tested 5 monitors (now using XG2402) and found an interesting phenomenon. When playing CS1.6 in the 75Hz mode of the monitor’s built-in 640×480 resolution, the input delay is extremely low. I can feel that the processing delay is 0!? Why is the input lag at custom resolutions lower? I am currently using XG2402. I tested the scaling mode at 1920 resolution, 100Hz, 120Hz, and 144Hz. There is obvious processing delay. This is already the best monitor I have ever tried, but it still doesn't work. Tolerable..

According to the chart, the KTC M24T09P has an average display latency of 6.57ms at 60Hz, 2.89ms at 120Hz, and 2.75ms at 165Hz, which means there is no noticeable delay between your actions and the results on the screen.
Why does this cheap monitor have such low input lag? It's the lowest I've ever seen on a digital monitor. But the M24T09P only costs $70. This goes against common sense. I need expert answers.

I need Chief Blur Buster, the main administrator of the forum, to help me with the answer. Thank you~