I have noticed that since January, TCGplayer has changed their mid price to show Median instead of Average. And I think this is a great change since makes the prices less vulnerable to being skewed by extreme outliers that occurs from a vendor under or overvalualing a card. It seems to me that deckbox still uses the TCG Average as default price indicator. Are there any plans to update this?

It isn't something that Deckbox has control over. They use the TCGPlayer API that returns the Average value. If TCGPlayer updates their API to instead return the Median, then Deckbox should follow suit.