How deep is that pot it's in? Papayas make a long taproot that goes usually straight down if they are in the ground. It may be hitting bottom on the pot. If it is, that means it's probably not getting enough water. Just watering more won't help the problem long term, and you absolutely do not want to sit it in a saucer - they hate to have "wet feet".
Any way you can turn it on its side and look in the drain hole to see if the tap root is visible? If it is, I'd say you need to first put more soil into the bottom of the pot, then start hunting for a deeper pot. Looks like you could add 10cm. or a little more? Pull the plant out of the pot, add the soil in the bottom then put the plant back in.
Bottom line is, this is the reason you really shouldn't grow papayas in a pot, long term. They continue to just get taller and taller, and also to grow the tap root longer and longer - which it needs in order to stay standing up as it gets taller.
Best solution, do you know anyone with a garden where you could plant it in the ground? Offer to care for it and share the fruits.
