Hey Oleg, thanks for reaching out! Rather, you won't lose the 3,433 credits, instead you'll only receive 6,567 credits when this next billing cycle occurs which will bring your account to a total of 20,000 credits.
If you have a monthly subscription, unused credits will roll over and accumulate in your account up to 2x the credit limit according to your plan. If you buy an annual plan, you get all your credits upfront, and you can use them however and whenever you’d like.
You can read more about the Credit Roll Over Update here. Let me know if you have additional questions! :)