A total of 135,685 people tested positive for Covid-19 in England at least once in the week to June 30, up 71% on the previous week, according to the latest Test and Trace figures.
It is the highest number since the week of February 3.
The latest data shows 5,185,145 people were tested at least once between June 24 and June 30, 2021 for Covid-19.
This is an increase of 6% from the previous week, The Mirror reports.
Mr Sunak told Sky News: "I've spoken to the Health Secretary about this and he's aware of the frustration that people have around this.
"I know most people's concerns rest with how the app is working, and the Health Secretary is aware of that.
"The app counts for the majority of the people who need to isolate, I understand, on the numbers, and he's looking at what the most appropriate, balanced and proportionate approach to isolation is in these circumstances."
He added on BBC Breakfast that Mr Javid will be "looking at the difference between those two systems" of the app and NHS Test and Trace.
Labour leader Sir Keir Starmer warned on Wednesday that the plans to end restrictions could lead to a "summer of chaos and confusion".
He told Prime Minister Boris Johnson that businesses fear "carnage" with the loss of staff to isolation, and people having to cancel social plans.
Some people have suggested they have deleted the app to avoid isolation requests for contacts with Covid-19 infections.
Changes to self-isolation rules in England will not come in until August 16.
Fully-vaccinated individuals and under-18s will no longer be told to stay at home if they have come into contact with a coronavirus case but will instead be advised to take a test.
People with confirmed cases of Covid-19 will still be told to self-isolate.
