End of GA and Start GA4

Hello, how do you approach the termination of sites with google analytics and when? If they have to finish then all non-professional projects will show zero.

But customers will switch to GA4 in less than a year, and we can’t show them zero, and they won’t want to pay more money now that they’ve paid one amount now.

We recommend purchasing packs of 12 credits to get a -40% discount and stock the credits when we have promotions.
So your average purchase price per credit will be lower, and you can continue charging your clients the same amount.

And what will we do with the fact that non-professional accounts will show traffic in GA4 only as from Russian-speaking countries?

We do not have traffic from Russian-speaking countries. It seems that you are confusing something.