Well, now after months of silence, I'm posting this picture related the issue that is affecting my rewards and points trough the arenas.
Once the multiplier is at 2.5X is already available the medium difficulty.
As soon as the multiplier goes on 3, like is normal for earn more points, the difficulty goes to easy and using the 5* Bot on a good level, I'm going to miss a lot of points, that are helpful for reach the milestones.
Those teams are from the game and I would them removed. Has no sense play at this way.
If the argument has been already discussed, I apologise for the post.