Looks just like mine when I’m running or physically working hard, usually as a result of heart rate rising and thus breathing more heavily. Heart strain may be more or not affected so I don’t worry over it. As long as it goes back to sinus.

It looks like you are having some noisy signal. Here are a few tips to improve signal quality: https://support.fourthfrontier.com/article/the-data-my-frontier-xx2-device-provides-is-either-inaccurate-or-poor-how-do-i-fix-this

Thank you for pointing that out. We have updated the link above.