HRV 7 Day Average

I'm trying to figure out how this is calculated. I have a different number displayed on my VA5 and FR165. They're both synced, so they should have the same average? What I have done is switch between wearing one or the other and sometimes both, but in the end the data should all be synced back and consolidated? I'm not sure which one is correct, and my own simple calculations work for some of the data, but not all of it.

Here's some data from Connect I gathered. The last two columns are my attempts to calculate a number for the 7 day average. I'm not sure what formula Garmin uses, but I tried just averaging the last 7 days overnight hrv, including and excluding the current day. E.g. for October 25 the range is 19-25 October. It seems to work, except for the last two days, in which case the VA5 may be correct?