Who I have the same questioned this topic

So My Verizon and my Data usage on my Galaxy S10+ show that I have exceeded my measly 4GB plan (which I've had for years and don't ever recall exceeding). When I go into Mobile Data usage at the top the chart shows my heaviest usage is 0.30GB, the next 9 heaviest usages and that top one add up to less that 0.75GB's for the month!

I have very few apps on my phone, and the data usage recorded on the phone adds up to another 0.6 GB's.

Most days I'm hooked up to my own home wireless network or my work wireless network, HOW can I be using 4+GB's when my phone only indicates less than 1.5GB's?

Yes phone is protected by Verizon's Security package, and I only get apps via the Google Store 

Data Saver is on, Mobile Data is off And my data usage shows I've used 6.84GB's of Wi-Fi data usage.