Check this out, is this correct? (just found this in a discussion on steemit):

Under HF20 a post receiving $1 in upvotes would give the author $0.75.

Under HF21:

The reward pool will be 10% lower to fund the SPS.
The CLRC will reduce the payout by a further 40% compared to linear.
The payout to the author will then be 50% (rather than 75%).
I make this: $1 * 90% * (1 - 40%) * 50% = 0.27 under HF21

So broadly: $0.75 under HF20 vs $0.27 under HF21, a reduction of about two-thirds for smaller payouts.