This is looking like a big year of substantial changes for the 2021 KX 250 and the most notable in my opinion is that now Suzuki will be the only brand with a kick start bike in the field. Kawasaki has now upgraded the KX 250 with an electric starter. Notice the lack of kickstart in the picture below.
The second big move in my opinion is that now Kawasaki has outfitted the KX 250 with a hydraulic clutch. This is a big move and all the Japanese brands I think will make the switch soon.
The 2021 KX 450 and KX 250 are getting many upgrades this year and this is by no means the comprehensive list for the KX 250. For detail and insight on the entire list checkout the link below.