What: Please either make Sticky Notes opaque or add transparency control.
Why: Sometimes I put Sticky Notes over top of another Sticky Note, to mask the text on the Sticky Note below. However, Miro has decided that one should be able to see through Sticky Notes.
NOTE: I need to resort to this technique as Miro does not offer native show/hide/flip Sticky Notes (another Idea). Sometimes I use 
The behaviour as of this post:
Hi@Robert Johnson .
Instead of masking sticky note with another sticky note, have you tried masking it with a shape and keeping it above the sticky note?
Yep. I just tried it. It will work.
Shape can take any colour and they have transparency control. You can even try doing the “revealing magic trick” by changing the opacity slowly to zero.