It is the same frame, it just the fairings are slightly different with the 2019+ having a bit of fairing just above the mounting point. however i do believe the 2019+ is slightly wider (someone might confirm).
I know for certain that Womet-Tech make a frame slider, the other companies might be a little behind being a new model.
2016 - Kawasaki - ZX-6R 636 (ABS)
Rear Wheel 129HP / ~96kw & 43ft-Ib / ~58nm
Mods: Two Brothers S1R Slip-on Exhaust, Decored OEM headers, LED lighting conversion (Headlights, Markers, Indicators), TST Industries Taillight light and TST Industries Fender Eliminator
Woolich Racing ECU Tune w/ Race Tools: Quickshifter, Launch Control & Pit Limiter
Planned Mods: Braided Brake Lines
2016 - Kawasaki - Z125 Pro
Mods: Yoshimura RS-2 Exhaust, Airbox delete with Short Ram Intake with Pod filter and LED Headlight and Markers Conversion