I think that the pandemic has had a huge effect on how people behave. Maybe people just forgot their manners after being isolated for so long. Or maybe they are so tired of being cooped up that they kind of go crazy. I see this more on the road than in person, though.
I only know a handful of kids anymore, but all of them are being taught basic manners like please and thank you. They are also being taught to speak up when someone is hurts them or something isn't right for them, which might be seen as rude in the past.
Finally, in my previous job (workers' comp) there were three things that helped me predict how likely someone was to be rude: 1) being between 50 and 65 years old was a minor predictor (maybe 20% more likely to be rude to me). 2) Making a lot of money was a slightly better predictor (maybe 40%). 3) The biggest predictor of rudeness (about 70%) was being toward the top of the totem pole in their organization, but not actually at the top. They were mostly major power-trippers. One once yelled at me for 20+ minutes for sending him a check that I was legally obligated to send him - and I sent the letter explaining that with the check - because he didn't ask for it. It's tax-free money, man, just enjoy it?
I think that a lot of the people who are able to afford WDW these days are more likely to be in that upper end of the ladder. They are used to getting their way, they are paying a lot, and on vacation, they answer to no one. It's a recipe for their worst behavior. Disney is pricing out a lot of the people who can't afford to be rude in their daily lives, so the ones with worse manners end up there in larger concentrations. If 1% of the people you run into are rude, it might not make much of a difference in your day. If it's 5%, that might be all you remember because they are louder and likely to be more in your face than the people quietly enjoying their day.
Wow, this was much longer than I planned. If you made it this far, congrats! I might be procrastinating on schoolwork right now.