There are for most resorts. I haven’t seen any for Poly CL. But I have had or seen discounts for GF, CR, BWI, YC, BC & WL for trips in May & September. Oh & Gran Destiny Tower CL. I never look at AKL so not sure about that one. We have no interest in staying there.
Discounts do not apply to *all* available rooms. Disney sets aside a limited room inventory (including CL) for discounts and those can sell out, even if identical non-discounted rooms do not.
When a discount drops there is flood of guests who either book a new trip or rebook their current one to get to the discount. Even though the latter leaves the same number of rooms empty, it removes a room form the discount inventory.
So, if looking at the Disney+ discount, that was announced in April and many discounted room categories sold out within days (if not hours). Between high demand and few discounts, they get bought up quickly. There are still discounted rooms available, just not every category at every resort.
BWI is very popular & AP, Disney+ & Disney Visa discounts have been out for awhile. There haven’t been any public discounts for end of August. I very briefly saw a standard CL room for late August/ early September when they were first released. But the only CL room with the discounts now are the garden cottages. BWI is so popular, the discounts were very quickly booked up. That said, keep looking because people cancel or change plans all the time. I have gotten YC CL AP rates 5 days before our trip. So you never know when something will pop up.
There are not many CL rooms at BWI now. When they reopened following "THE" closure, they removed a fair number of their rooms. almost all of the rooms outside the Inn Keepers door.
But keep checking. I've book all 3 of our recent stays very last minute. With discounts. AP discounts but with discounts. So rooms do pop up even when it's been otherwise sold out. In all 3 instances I had booked other resorts initially but kept checking and found BWI CL rooms eventually. This most recent trip I got a Deluxe room just last week. And there are only 10 of those. And I got it for July 4 week. So miracles can happen.