Assuming those red dots are on top of the piece of teflon plastic, then I would assume that it is projecting dots (white spots) on some of the later layers. Due to the space between the build plate and the teflon, they wouldn’t attach to it, and thus would sit at the bottom of the resin vat (e.g. on top of the teflon).
First thing – have you looked at every image to verify that none of the layers have white spots in your png files?
Second, I would try these steps:
1. Take the projector out (to make this easier to see) and place it on a table.
2. Set a box or piece of cardboard in front of it, about 6-10 inches away from the lens of the projector.
3. Start the projector – do dots appear on the cardboard?
4. Change the throw distance (making the white rectangle larger or smaller, depending on how you spin the throw dial) – do white dots appear on the cardboard at all distances, or just some of them?
A video of that might help to see what it looks like in the process.