Probably both ways. Some kids backslide with academics at that age, others seem to gain traction. I didn't mention it but have considered that part of the reason that things became easier for me in the 8th grade is that I was starting to get the mental maturity to think more abstractly and deliberately.

I have a similar story, and puberty was definitely an issue. I didn't get good at math until I was old enough to buy alcohol.

This could be read as "once I needed to figure out how much alcohol per hour I was earning, I learned math".

Which means we just need to make kids play Factorio or Eve Online to instill the desire to be good at arithmetic. Granted, Eve Online would instill other behaviors that might not be so desirable...