I'd stay with the i9-9900K for a while as long as it is performing well for you.
It will still be a while before the reviews are out for the Ryzen 5000 CPUs.
Once they are you can read them and see if they will be a big enough improvement to make them worth the cost for you.
You mean to say, I should use my current beast
32 GB Ram , SSD, 2080 Ti
Performance vise it is actually very good but due to Windows and my motherboard’s issue my PC sometime lags minorly, because of that issue I have to change my current motherboard so I think your suggestion may be to buy Z390 am I right
I am not suggesting you buy a Z390 based motherboard, at least, until I know the make/model of all of the rest of your specs.
What is your current motherboard?
Why do you think it is a cause of a minor lag?
Do you have any budget constraints?