Same here with the Bosch Activeline Plus system. Seems the manufacturers are cutting the assist short on systems probably for liability reasons. I'm not at all surprised people are tuning their bikes to exceed the manufacturers limitations, especially when many ebikes seem to top out before they're supposed to. For those of us who would actually like to stick to the ebike category limits (1 in my case at 20mph) I'd like to see tuners come to market that let you limit the top speed, not simply deactivate limits altogether.
Bosch and Cannondale (my bike manufacturer) are passing the buck back and forth saying that the other one is responsible for correcting speed assist issues... meanwhile nothing gets fixed. It's very frustrating. If we had an aftermarket option that let us tweak our ebike systems, but still stay within category speeds, that would be perfect. Like many of the farmers who are frustrated with John Deere, I'd like to be able to finetune and fix my ebike as needed in my own workshop.