Finally, I get to drop this information I’ve been holding on to.

In the episode where Phineas and Ferb went time traveling, at the end of the episode Present Candice successfully busts Phineas and Ferb in the future to their future mom.

Problem is, she reacted as though she had no idea, and solidified that this was the first time she ever knew about their antics.

Unknowingly, Candice created a fixed point in time which made it impossible for her to ever successfully bust Phineas and Ferb for the rest of the series.

There are close calls, takeout dreams and more, but they never last or they were never real.