pay back

1. (transitive) To pay (a debt or the lender) so as to provide the entire amount of money owed.
2. (figuratively) To avenge, to exact revenge.

Here I am using the 2nd meaning.

It was signed in 2024.

Well, yes. Countries had an agreement, and some of them broke it unilaterally. How Russia is to pay back for that is the open question.