I checked earlier in the week but never saw the discount anywhere. Where was it supposed to show up?
It was available in the main SpriteMancer page: https://codemanu.itch.io/spritemancer
Did you receive the email I sent about SpriteMancer release for old customers?
I received 2 emails for owning 2 other products (on Jan 9th, for Juice FX & Pixel FX), that stated, "From Jan 16th to Jan 22nd you will be able to get SpriteMancer with a 100% discount on Itchio." But when I checked on Itch on the 16th I didn't see any discount anywhere, checked again yesterday, the 22nd, and similarly didn't see any option to claim a copy.