Simple wiring problem (I hope)
Don't break any tabs unless you are sure you want one half of the receptacle unit switched and the other half live all the time. And you are sure you have switched power and unswitched power at the outlet box.
How was it wired originally? (which side or end did each white wire use to go?)
Maybe some of the wires got spray painted when the walls were painted, thus making them white or off-white.
The disadvantages of crab apple trees. In summer, the apples are too sour to pick and eat. In winter the birds come and leave dropping all over the place.