Please refer to full scores when talking about the average - +-Par is ambigous, thus makes no sense.
Your latest scores were 31, 33, 29 and 31 while your average is 64.10 - we don't know if it's saturated or not.
The score are doubled to 58, 2x62 and 66 - the latter above your average. These scores are a good representation of the scores shown in your history - some 27s are from Bo3 and do not count.
The most important change over time is the number of scores in the pot. For average calculation, it is in the denominator, and the big numbers (up to 500 for Legends) cause unexpectedly small results.
Imagine that you might be at 300 rounds now(?) A 62 would count in as about -2/300 = -0.067 - barely visible in the display.
The 58 might result in -6/300 = -0.02, or less if you have more RRs as a Legend.
This is how it has been "forever".