Ok, when you're Mandela Effect hunting you often have to look for "reality residue" that supports your theory that this stuff was once something different.
The controversy here is over the lyrics in the intro song for Mr Roger and Daniel Tiger.
In Mr Rogers Neighborhood it's "It's a beautiful day in this neighborhood." In Daniel Tiger the lyrics are "It's a beautiful day in the neighborhood."
People experiencing the Mandela Effect swear the line has always been in both shows THE neighborhood. THIS neighborhood is a shitty line. It's like it's only nice for Mr. Rogers and everyone else doesn't have a beautiful day. It doesn't make any sense.
Ok, so now here are two shows that reference the line directily. Mr. Robinson's Neighborhood which was a skit on Saturday Night Live by Eddie Murphy where he uses THE Neighborhood in 4 different episodes spanning 2 years. We also have it on Daniel Tiger's Neighborhood.
The tricky part come the battle of when you see Reality Residue like this is it evidence that people had a different reality elsewhere or is it evidence that things exist in the world that would trick people into misquoting lines and misremembering lyrics.
To the people that grew up watching these shows over and over and knowing the context changes that word changes imply there is no way we just misheard it. To the people in this reality they seem like "nutters" who can't figure out a line that's always been that way. I personally think both realities existed and somehow they merged and now people grew up experiencing one or the other.
Anyway, especially since Tiger was a character on Mr. Rogers Neighborhood and the whole show is basically a spin off you'd think they'd be able to get the theme song right, but Mr Roger's and Tiger's/Robinson's intros are different. That's "Mandela Effect proof."