It is not clear that the downgrade refund -- not compensation -- is based on the fares in effect on the date the Mint seat was booked. B6 follows common industry practice and this means that refunds are close to meaningless.

Nonetheless, agreed that it always makes sense to screenshot the pricing page when making a booking. It makes for better advocacy later and -- who knows -- a new DOT might change the rule and define what it means by refund for "downgrade".