Before jumping to conclusions, I think it is necessary to measure the models. Comparing a new model to an old one doesn't mean the old model was correct so if the new model is different, it isn't automatically wrong.
In this photo it looks like a Stuart is being compared to a standard suspension Sherman. Note the height of the front mud guards on both. and the overall height of both tanks. There is a small difference. Overall height of a Stuart was 257 cm vs 274 cm for a standard suspension Sherman. The difference is only 17 cm or 6.5".
In the photo of the models, a Stuart is compared to an Easy 8 with an HVSS suspension. The Easy 8 tank is 30 cm taller than a standard Sherman or almost a foot taller, mostly in the height of the suspension. The HVSS Sherman is 40 cm taller than the Stuart - look at the height of the front mud guards. The difference is much bigger than in the first photo.