It's been may observation that pretty much all fast food places have seen a decline in quality of their food. Staleness, dryness, blandness seems to be universal.
The decline happened gradually over time so we didn't notice it as much but if you were to take a time machine back to any of the fast food chains during the 1980s, you wouldn't even recognize the food from what they're selling today.
I'd attribute is mostly to cost cutting in labor. These places operate with a fraction of the crews that they used to leading to more ahead of time prepping and storing their products in warmers where they dry out instead of cooking them fresh.
This. When I worked at McDonald's about 50 years ago, the burger patties went straight from grill to bun. Now they cook a lot of them and then stick them in heated drawers until it's time to assemble the burgers. The difference is very noticeable.
And yes, there were easily twice the workers during busy times.