5050 led strip 60 led/m flickers when fading in and out of colors
The LED Driver/IR Receiver uses Pulse Width Modulation (PWM) to set the brightness of the individual colors. PWM works by quickly turning on and off the Power to the individual color channels with a duty cycle of \$R=\frac{T_{on}}{T_{total}}\$, where \$T_{period}\$ is the period of the turning on-and-off.

For example: A duty cycle of \$50\%\$ means that the LEDs are on \$50\%\$ of the time, a duty cycle of \$20\%\$ means that they're on \$20\%\$ of the time.

Usually the value for \$T_{period}\$ should be picked to be as low as possible to prevent visible flickering, especially when the LED is moving across your field of vision. When \$T_{period}\$ is too long, flickering will be visible, especially at lower duty cycles which occur when a color if fading out.

On very cheap controllers the electronics aren't capable of a short \$T_{period}\$, and the only way to fix it is to replace the controller with a better one.