By what mechanism is that recovery supposed to happen? AFAIK students who studied less during the pandemic weren't made to study more later to compensate, so by default they'll permanently have done less studying than other cohorts at the same age.
I think the pandemic had some effect on the current cohort of 15 year olds, but it should not be as large of an effect as the students who were 15 in 2020.
If I missed a week of math class at age ten would it have the same effect on a test given when I was 15 as if I had missed a week of math class just before the test? Your position seems to be that missing math class at any point in your schooling is a permanent unrecoverable setback
A student who is bad at arithmetic will tend to struggle to learn trigonometry. A good teacher can realize this and allocate time to arithmetic practice instead. But this time has to come somewhere. As long as the number of teaching hours remains the same, they have to sacrifice something else. So if the students are all caught up in arithmetic, they will be behind in trigonometry by the same amount.
To fully catch up without sacrifices, students who studied less would need to study correspondingly more to compensate, but there was no concerted effort to make that happen, although the opportunity certainly existed.