For what it's worth... we have had a very very very large amount of 2020s in for service for all sorts of crazy issues.. mainly a bunch of electrical problems and some being bad enough to debilitate the vehicle.
I can count the number of 21s that have had issues on one hand.
This is for all Explorers in our service department but the only STs that I've seen in service that have had issues have all been 2020s.
From being on the dealership side.. the 2020 is by far least refined of the three model years.. mainly interior fit/finish and materials used and crazy amount electrical bugs.
Matte black plastics are HORRIBLE compared to the gloss black they added in 21.
21 seat trims aren't snapping and breaking off.
Haven't had a single 21 with transmission issues.. have seen 3 2020 STs with transmission issues.. 1 being the old vehicle of our finance manager.. his 2020 was one of the worst Ive seen but I have a few customers who are having pretty bad issues with their 2020s.
Not trying to knock the 2020s... just putting my two cents in for seeing first hand different issues with model years.