If (like me) you bought a steam deck right before the announcement of the OLED version and the price drop for the original, you can contact steam support, tell them that if you knew about the coming price drop you would have waited, and request a refund for the price difference.
I paid £369 for a refurbed 256gb steam deck, then they lowered the price to £279, and I just got £90 refunded to my steam wallet this morning after contacting them yesterday.
I got a refurb 512 deck the week before, opened it 2 days before the announcement. FML
I have just asked them if they would let me return it so I could purchase a new one.
I will let you know what happens