I'm not sure how they determine those numbers, wonderfully turnstile-free as they are. But 2021 definitely felt crowded. Also ops on Dominator seemed horrible but a lot of it appeared to be newb factor. It was always something, people finding out they're too big now, chickening out, trying to wear hats, you name it.
All of the major rides have a button on the op panel that counts open seats per dispatch so it's pushed for every open seat on each train sent out. Then at the end of the hour the ride spits out the total ridership for each hour along with the number of dispatches.
Don't think of it as something super fancy because it's only as accurate as the ride's programmed clock time is.