From your 2021 MCME Online module on Capnography:
Capnography waveform can help you optimize your ventilation technique. The following waveform shows hypoventilation by the provider, with the ETC02 rising. If you see this, reassess your mask seal, technique and ventilation rate.
Check out the 2021 MCME Precourse on Capnography for more great tips to help your practice.