Samsung Galaxy A11 constantly exchanging data on WiFi

I don’t know the answer, but have you tried checking which apps are constantly exchanging the data (on my phone this shows in Connections → Data Usage → WiFi data usage) and how much data are they exchanging?

Also, some apps ask if we want to allow diagnostic data sent to them, which I think is usually optional. If this is happening, you could select no.

Or, maybe trying another anti-virus could help, to confirm that there is no virus that stayed undetected in Lookout?   

Hi! Maybe it depends on phone model. My phone is Samsung Galaxy A14. On my phone it is: Settings → Connections → Data Usage → Wi-Fi Data Usage. Do you have a similar option? What shows on your phone? 

Also, maybe apps are updating automatically (I think this is default option). In Play Store → Settings → Auto-update apps, you might be able to choose if you want apps to update automatically, and if yes - if this would be over Wi-Fi only. However, it is good to keep apps updated, so that they function properly.     

If useful, on my phone, two apps that use the highest amount of data are Google Play Store and Meta App Manager. Galaxy Store also uses a lot of data. 

Hope some of this helps.