About symmetry

Most indicators, in addition to lag, have internal symmetry. If the oscillator signal was confirmed by the price movement, then the signal symmetrical to it is likely to be false. Especially clearly symmetry is manifested in short-period oscillators.
The rules for identifying mirror signals are different for each indicator, but the general principles are:
the main (already past) signal is confirmed by the price
the price crossed one of the axes of the indicator (for example, MA used in the calculation of the indicator)
no more than T has passed from the moment of the main time signal (as a rule, the indicator period is + 10%)