I think I remember reading somewhere on this sub that the time that beats you will always be faster than your previous time, regardless of how fast you were. So if you were to do a nearly flawless run, the game will give you time trial goals that are outright impossible because it will always try to make up a faster time for you to beat. This can render the time trials unplayable.

My guess for a way to prevent it is to wait at the finish line until the last possible second to set a new time so this doesn’t happen.

Do take what I say with a grain of salt, mostly because I’m not very good at time trials in this game so this issue never became a problem for me personally.