[BUG] Alternate between dot projector and illumination LED when adjust the image frame rate to 60Hz

[yyh-pc]

In examples/MonoCamera/mono_preview_alternate_pro.py
example script will run both left and right monochrome camera sensors at 30FPS, and it will switch between the IR LED and dot projector every frame - meaning we will get LED-illuminated frames at 15FPS, and dot projector-illuminated frames at 15FPS.

But when I try to set the fps to 60, the part of the script that checks for left and right image frame time synchronization always reports an error like this:
1844301011CD3BF500] [3.2] [6.534] [Script(6)] [error] frame/event desync! Fr-Ev: 1 frames, 16.667 ms; R-L: 0.013 ms
[1844301011CD3BF500] [3.2] [6.551] [Script(6)] [error] frame/event desync! Fr-Ev: 1 frames, 16.667 ms; R-L: 0.012 ms
[1844301011CD3BF500] [3.2] [6.568] [Script(6)] [error] frame/event desync! Fr-Ev: 1 frames, 16.666 ms; R-L: 0.013 ms
[1844301011CD3BF500] [3.2] [6.584] [Script(6)] [error] frame/event desync! Fr-Ev: 1 frames, 16.667 ms; R-L: 0.011 ms
[1844301011CD3BF500] [3.2] [6.601] [Script(6)] [error] frame/event desync! Fr-Ev: 1 frames, 16.666 ms; R-L: 0.011 ms

The parameters are set as follows:
if 1: # PoE config
fps = 60
res = dai.MonoCameraProperties.SensorResolution.THE_400_P
poolSize = 25 # default 3, increased to prevent desync
else: # USB
fps = 30
res = dai.MonoCameraProperties.SensorResolution.THE_720_P
poolSize = 8 # default 3, increased to prevent desync

I tried to change the poolSize parameter but it still doesn't work. How should I fix this problem?