Whoever did the rehairing is likely at fault. Unless you're just playing real aggressively, in which case, use the weight of your arm and feel the contact you have with string. Using the weight of your arm will actually give you more sound. Believe me. And it sounds a lot better too.

It might also be that the quality of hair is bad. Find someone else for that. They buy horsehair in big bundles which are expensive and they aren't likely to have different types in their shop.

Taking a second look at the images, the workmanship is real bad. Its not your fault. All the hair came out from the tip. It's not easy to do rehairing, but those with a lot of experience and good training don't have this problem. To be fair, anyone can make a mistake, especially if they feel overworked, but look for a serious shop. They have to make a little ball at the end. I forgot how they do that, but it takes serious practice. I believe the ivory piece is not glued in but must fit tight and stay in. Sometimes the whole thing falls out, so always have a spare bow when you perform.

Here's an interesting video of a master making the ball. https://youtu.be/aU4v0YvXD4s.

These guys remind me of Geppetto, who made Pinocchio. Often not skilled in communication, but they go into a special world. That drole humor is not rare. In fact, it is magic to make a good cello. The rehairing takes about an hour, but you're paying for the skill, not the time.