Often with a revamp, companies will add in more glitz, images, extra scripts for animation or sliders, extra code for additional functions … make sure you understand the speed and bandwidth changes, and make sure the new version won’t lose scoring on page speed or CWV.
Final note is always keep your eye on the real prize. A lot of people will shy away from a change that drops traffic by 10% even when it raises conversions by 30%. Don’t be one of those people. Total conversions is always the ultimate bottom-line metric.