Nothing special. Mana Reflection is the only other existing mana multiplier that isn't a triggered or activated ability. With Sasaya's Essence, Nyxbloom Ancient, and 4 Forests, each Forest would tap for 3 and then Sasaya's Essence would trigger and produce 3 more. As opposed to without Nyxbloom, each Forest taps for 1 and then Sasaya's Essence triggers and produces 3 more.
Now, if you have Mana Reflection and Nyxbloom... each permanent tapped for mana produces 6 times as much as it should.
Waaaah!
There go my dreams of tapping a single Forest for GGGGGGGGGGGGGGGGGGGGGGGGGGGGGG :’(
You can get closer if you run Bramble Sovereign to copy it and Temur Sabertooth to put it into your hand and do it again!