Internet Data usage spike

When I checked data usage on my first day of the billing cycle, It was 57GB @ 4PM, 60GB @ 5:00PM, 64 GB @6:00PM and 66 GB @8:00PM without having any significant use of internet (see graphs below). I have never exceeded the 1.2TB even when I have two kids remote learning via zoom for the whole year 2020-2021. The spike started at the end of MAY and continued through June. I realized the spike when I got a notification that I used 75% of my data. I limited usage to the bare minimum checking email only for the last week of June but the data usage continued to be 40GB - 50 GB a day. I have attached the usage graph for reference. almost 0 usage from January to April and started spiking end of MAY  and continued in June and July. Something is broken here.