The ball speeds up, but it has a ceiling
Every brick you break nudges the ball faster, and the game is upfront that this is deliberate - it is meant to get harder as a level empties out. What it does not advertise is that the increase is not constant. Each hit adds less speed than the last, following a curve that flattens out as the ball approaches roughly one and a half times its starting pace, and it never goes past that.
The practical effect is that the panic point comes earlier than you would expect and then stops getting worse. The scariest-feeling stretch of a level is usually the middle, once the ball has picked up real pace but before the increases have tapered off. The last few bricks, despite being the fastest the ball ever moves, are not accelerating anywhere near as quickly as the first dozen did.
Knowing that changes how you should play the opening of a level. There is no reward for rushing early bricks before the ball 'gets away from you' - it never truly gets away from you. Taking clean, controlled shots at the start costs you nothing in difficulty later.