When you first onboarded your account, the system downloads advertising data from the past 60 days.
So if you onboard your ads on 1st January 2022, the earliest available ads data is around 2nd November 2021.
If you look at the sales dashboard or sales trend that includes days without advertising data, the overall ad cost/sales will be lower.
If you go to the "Sales by Date" tab, you can see days without Ads data.
However, Scale Insights does not remove data for accounts with an active subscription.
It means you will always have access to all your data, even years later, as long as you have an active subscription.