Interestingly enough, I was just going to make a post about this exact same problem, so I'll just piggyback onto this thread with the hopes that somebody can help both of us out.
I actually have two toilets. Both are Dometic 310. One of them works properly. When you flush the water comes out of the jets nice and slow and creates a swirling action into the bowl.
With the other one the water comes out of all the jets at a much higher velocity. Most
of the water stays in the bowl (especially with the lid closed) but it does have a tendency to splash outside of the bowl as it hits the sides.
I don't have a water pressure regulator (Yes, I know I probably should have one but I've been in my seasonal spot for almost a year with no problems) but the pressure everywhere else in the trailer is just fine. All the sinks and shower work as they are supposed to.
I've tried cleaning out the jets but I find it hard to believe that they would ALL be clogged.
I was actually wondering if it was possible to get a pressure regulator specifically for the toilet but I don't know if they make something like that.