Legal regulations for eBikes

Hey everyone!

I've been diving deeper into some DIY upgrades for my Class 2 fat tire eMTB, thinking about bumping up the motor's peak power, but it got me wondering about the legal side of things. Specifically for those of us who like to tinker, what are the rules around modifying motor output or speed limits, especially if it pushes you into a different class? Has anyone here run into issues with local regulations after making modifications, or found good resources for staying compliant while still getting the performance they want? I'm curious about experiences in different states/countries too!