I'd replace the broken ones and then true the wheel with the proper spoke tension. There's videos available or bring it to a bike shop.
As already stated, it's the most common cause so replacement isn't going to solve the problem unless you true/tension properly.
Also check this from the...
I have my Zen PAS 1 set so low, it feathers in 25 - 100w. You can definitely get a workout if you want one. I have the first 4 PAS set to be very subtle and each increase is just enough to make a small difference and keep you pushing.
PAS 5 - 9 and now we're talkin' crack pipe power. 🙃
I see no reason an ebike has to emulate a conventional one closely. I enjoy the extra power and speed of my ebike though I typically ride in a very similar speed range. Speed is addictive but torque/acceleration is a glowing crack pipe! 🔥
That said higher voltages will typically yield better...