MY19 is a 68 & 19 plate. And was first release of the 3rd phase of the PHEV (Sept 2018 release).
MY20 is a 69 & 20 plate. There were a few big changes to the interior. (Sept 2019 release).
1) Larger touchscreen.
2) Redesigned heating switches.
3) Eco button and seatbelt warning lights etc moved.
4) Loss of heated windscreen.
5) Maybe more stuff, but unsure.
MY21 will arrive in UK in Sept. no news yet but expect minimal changes as should be last model year in current design/chassis.
MY22 will arrive in Sept 2021. This should be the all new Outlander, with shared platform with Ren/Nis.