Not directly, it isn't caused by Prostap - the GnRH drugs do mess with your metabolism and can cause gastric upsets.
The most important issue to be very careful of with Prostap and the digestive tract is Too much sweating from hotflushes - causes dehydration, and not taking onboard enough water to top up.
If you don't take on extra water - a small glass for every hot flush to replace the loss from sweating you are going to alter the fluids in the gut - and that usually means a touch of constipation - slowing down of transit of waste. Dehydration is also known to cause a sore tummy which might be misinterpreted as indigestion. It will increasingly cause a lot of problems, with heart rate, circulation and peeing too. If your pee is darker than it usually is - it's another sign that you don't have enough fluids onboard for what your body is needing which is concentrating the wee so it looks darker.
That would be the first thing to look at rectifying - increase fluids onboard, there's no need to overload the body - but a small glass or a few mouth fulls for each hot flush should be enough. you don't have to drink after each one -but if you hot flush three times and hour then have a tumbler of water. The more frequent the hot flushes the more you need to top up.
Water or milk should also calm the acidity in the tummy and calm any gut irritation from too much acidity and keep the bowels moving better too. Extra water will also help with production of a mucus lining of the stomach to protect it from the stomach acid causing indigestion.
So try that as the first step.
You can take gaviscon and other ant-acids to see if that helps ease the irritated stomach lining too.
If you have recently been on certain anti-biotics or other drugs that must be taken with food or water then it may be that you have managed to form a small peptic ulcer. It will heal with TLC and time, and making sure you keep stomach acid levels down.
If the extra water intake doesn't resolve the situation in a few days then see your GP.
There are bacterial infections that can cause problems inside the stomach but don't cause the runs, like helicobacter pylori.
But my hunch is dehydration is probably the most likely issue with Prostap and it's side effects.
Hope you're feeling better soon - at least as well as you can be while being on Prostap.