I don’t have historical pricing on movies theatre snacks available off hand, but I would be willing to bet money their pricing is 100% consistent with what it was 15-20 years ago as well.

Movie theatre popcorn and drinks have always been over priced (at least in my lifetime) and have always been where theatres recoup a ton of costs.

If anything, these days theatres shouldn’t have to charge quite as much for popcorn now that they can make money selling alcohol and food and such as well.