MacBook Pro (16 inch late 2019) almost unusable with MacOs Monterey

In February 2020 I got Mac Book Pro 16 inch (late 2019)

2,4 GHz 8-Core Intel Core i9

32 GB 2667 MHz DDR4

AMD Radeon Pro 5500M 8 GB

Intel UHD Graphics 630 1536 MB

I got it with macOS Catalina (version 10.15).

It was the fastest laptop ever - for about a year and a half. With another OS update (Big Sur) it started being unresponsive, got incredibly slower and my Adobe Suite will freeze and crash, etc. Yesterday trying to speed it up I installed Monterey ( honestly was afraid to install Ventura which is officially recommended). My Mac is unusable practically. Even my screenshot is buggy, delayed and the preview icon takes a lot of time. Powerpoint work was a nightmare. I wasn't even trying to use any of the Adobe programs.

Does anyone know what this could be? I am aware that after this one apple started using new chips and the updates are optimized for them. But this never happened to me. In just 3 years from the latest upgraded model, this became an unusable Mac.

Does anyone have the same problem? Maybe I ve missed something? Is there something I am doing wrong?

I was thinking of downgrading back to Catalina or getting a new one as soon as I can afford it.