Whirring sound from rear area of my 2013 outback

Replace wheel bearings

Thank you. Another question, after further reading, does subaru have a recall for the transmission in the 2013 outback ?

Save some money and try to distinguish WHICH side rear bearing is noisy. If turning each doesn't help use a stethoscope. The bearings wear idiosyncratically, so there's no sense in replacing both. SOA extended factory warranty on CVT to 100k...which is NOT long enough!

Further: if a whirring sound is NON-correlated with speed linearly, and seems to come from the front or middle of the chassis instead of the rear, it's apt to be a worn CVT rather than FRONT wheel bearings. This can be trickier to discriminate, as the sounds can mimic each other. But given the overwhelming preponderance of under-engineered rear wheel bearings you probably have a bad one. USUALLY it's the right side...but not by a wide ratio, so check left and replace the louder side.