Oddly the good stuff wasn't much affected. I was making a work bench and picked up a 4x8 of red oak plywood for under $60 in May. Not what I would normally use but half the price.
Now that I think of it, it kinda makes sense: it's not the timber that's gotten more expensive, but the service of milling it. For products from relatively more expensive hardwood timber, milling costs constitute smaller fraction of the final cost, so even if milling costs triple, the final product might only go by 50%.
I'd guess (with some insider knowledge) that (1) there wasn't any prebuilt link to adjust substitute pricing & (2) Depot didn't care enough to adjust pricing.
Both Depot and Lowes are in it for volume and long-term, which is why they don't do things like spike generator prices after hurricanes.
Imagine you've got a project to build a bookcase. You're using cheaper normal plywood for hidden structural parts and nicer but more expensive red plywood for the stuff people will see. You price the whole thing out.
Then the price of wood skyrockets. To keep the price of the whole project under control, you start cutting costs. You use more of the cheaper plywood for the whole project and decide to skimp on the red oak.
Scale that across many projects and you get a paradoxical result where the cheapest goods in a category go up in price while the better goods don't, because people are subbing out the "cheap" stuff for the good stuff.
Modern glues in exterior plywood and OSB-like products are amazing, but they don't use that in oak plywood.