It's really not fair on Cordova apps and it's not fair that all the great App Store games made with Construct 2/3 gets affected by this - please file the bug! If they wanted to save that much battery then my guess is that they would already have implemented a fps throttle for native apps as well. There are some really big battery draining games out there!
33 fps is a horrible experience! it makes you think that your device is broken Nor does anyone that develops games for their devices. It's a really hard thing to explain to your users.
Low power mode is fine but I would say that the fps throttle is a very big problem for game developers that are using Cordova and releasing games on the App Store!
Do you think there's a specific reason that they have implemented this 33 fps Safari throttle, or just a general thing to save battery? Hopefully they can just remove it!