Insanely high FaceTime bandwidth usage

I was recently talking to somebody on FaceTime (connected to a wifi network) when I noticed afterwards that the amount of data used for this call was incredibly high.

I talked to the same person earlier in the week and data consumption stayed normal to whatnot I had seen over the Internet (~3mb per minute). However the rate at which bandwidth was used in these calls seemed to rapidly change.

I am connected to a wifi network however my plan has limited data so a solution to this problem would be greatly appreciated.

Here is a screenshot for reference:

Also, I am using iOS 11.0.3

Thanks in advance,

Andrei