Renko chart disadvantages include lagging signals, no time or volume information, false signals in choppy markets, difficulty selecting the right brick size, and limited intraday detail.
Because a new brick only forms after a significant price movement has already happened, Renko is a lagging indicator, which may result in much of the move already occurring before a signal to enter, especially on lower timeframes.
Renko charts generally lack volume information, which is essential to identify potential reversals and confirm trends; without it, making decisions based purely on the chart is difficult.
They also struggle in range-bound or choppy markets where false reversals stack up.