You will have achieved a new seasons best average power for 5 minutes whilst completing your over/unders. If you take a look at the power curve for your ride then you will be able to see if the power curve lines up with the seasons best power curve at 5 minutes.
I can’t see the activity, but I assume you averaged 260W for 5min at some point.
Depending on your phenotype you may find much easier to break thru (or push the envelope) with shorter intervals and little recovery, rather than a single interval.