The only place I can remember being specifically asked if we had a tiw or any other discounts was Via Napoli and I do believe our service suffered because of it. He was kind of pushy about asking and when I told him we had tiw it was like a switch went off and he couldn’t be bothered to do any more than the absolute bare minimum from that point.
Another place we had trouble with service was ‘Ohana. We weren’t asked about discounts but did have a party over 6 so automatic gratuity.
These could both be coincidences, but we usually have excellent service at Disney so I wouldn’t offer up any discount info ahead of time personally.