I don't understand this change.
With current hybrid F1 cars the ERS deployment is automated, drivers do not have press any buttons like with pre-2014 KERS system. They can however change the way the car deploys ERS for different situations, like if they defending or attacking or just hotlapping in qualifying. They can also increase or decrease the rate of regeneration from the rear axle when braking. This is pretty much how ERS management works in F1 2019 (without regeneration setting and everything else also simplified). In addition to all this drivers also have this "overtake button" which turns everything up to 11 for a short period of time if they need it.
Adding overtake button in F1 2020 is good change but I don't understand why they removed the possibility to change ERS mapping on the fly. I suspect it might be in order to nerf players performance against AI or something like this. Pro players at least seem to fiddle with fuel mixture multiple times per lap (which is a whole another discussion).
Now if you can create your own ERS mappings then, that sounds interesting but still whats the point if can't cycle through them during a race?
