Berry feeding limit?

The cap has not changed.
10 different mon per 30 min. Each mon can be fed up to 10 berries. The limit is rolling, as soon as 30 min has passed since you fed the first berry to the first mon, you can feed something new, or feed more to that same mon, but need to wait until 30 min has passed since the first berry to the 2nd mon until you can feed a new one, etc.

You fed 10 different mon, so you hit the cap. You could still have gone back and fed all the mons more, until each had gotten 10 berries.

I have experienced this as well. There seems to be a secondary total cap besides the 10 per defender one. I am trying to take the last 4 local gyms that I'm missing to gold, so every morning I berry spam them if they survived the night. After feeding somewhere around 20-30 berries to different defenders, I reach a cap and am unable to feed any more berries to any other defenders in any gyms.

I also have hit the cap recently, and I only just entered the gym. I fed 3 berries to others and then my own one I could not feed. It appears that the berries that others have fed count towards a cap for the entire gym.