Demand did change though - people weren't pooping as much at offices, restaurants, and retail stores. All those places tend to use "commercial" toilet paper that is not available in your average grocery store.

If you looked at commercial suppliers during 2020, you were much more likely to find available supply, though it may be a bit awkward using one of those giant rolls at home when it won't fit on a standard dispenser.

It was my understanding that because most businesses were closed for an extended period of it the TP-production companies had to shift their production lines from the god-awful paper typically used in commercial settings to the paper typically used in homes.

A few weeks into the shelter-in-place order, I did see commercial TP appearing on the shelves in my local corner stores. A while later, I started seeing household TP appearing again.

I'm not claiming that there was no hoarding, nor that there was no profiteering by folks buying up lots of stock and selling "on the street" at inflated prices. I am definitely claiming that closing most businesses for an extended period absolutely changed the underlying ratio of crappy commercial TP to better home TP required... which apparently isn't something one can respond to overnight.

"For months" is surely an exaggeration? What has changed in supply and demand is that much less toilet paper had to be distributed to workplaces, and much more close to people's to homes.