Can we expect any rewards , for participating in them in Q4 2023?
Honestly with the past results of some testnets, users were discourage to do some of these task due to low rewards. Example of these are sei which has a very low value due to massive participants and a very few alloted budget for the testnet. Also the sui which chosen to do a random whitelisting which ignored the testnet users full activity and opted to do a small group of people reward by random lottery. Well some also low class projects giving a false hope and only non valued nfts.
Participating in testnet this days at your own risk. Although since money isn't involved, one can just risk it out if you don't mind wasting your time on it. The problem here is no one know which testnet will pay so you must try to do all that comes. Since the day of SEI and sui, I hardly partake in testnet. This is because it's time consuming and no one knows if they will eventually pay or not.