Need Help for configure 4 inch screen on pi4 and PCP6

Hello, I have pi3 with picoplayer 6 to install on it. I also have a 4 inch screen from the brand "waveshare": https://www.waveshare.com/wiki/4inch_HDMI_LCD

After configuring the config.txt file on picoreplayer, I have the display that works correctly through the pi3's HDMI port, jivelite also works.

I just bought a pi4 and I connected the screen still in HDMI to the HDMI0 port of the pi4 and I have nothing displayed on the screen. Not even the rainbow when booting the pi4 .
And yet picoreplayer starts well, I can listen to music without problem.

I then decide to connect the HDMI0 port of pi4 on my 65 inch Sony TV, the display works correctly, jivelite too.
Just a screen orientation problem, but it doesn't matter.

I specify that the 4 inch screen is powered by an external 5v power supply and not by the pi4 usb port.

I then reconnected the 4 inch screen to the pi3 and it works.

There is therefore a driver or parameter problem in config.txt to operate the 4 inch screen on the pi4.

Here is an excerpt from my config.txt file :

#Custom Configuration Area, for config settings that are not managed by pCP.
#pCP will retain these settings during insitu-update
#---Begin-Custom-(Do not alter Begin or End Tags)-----
#hdmi_ignore_edid=0xa5000080
hdmi_force_hotplug=1
hdmi_group=2
hdmi_mode=87
hdmi_cvt 480 800 60 6 0 0 0
hdmi_drive=1
dtoverlay=ads7846,cs=1,penirq=25,penirq_pull=2,spe ed=50000,keep_vref_on =0,swapxy=0,pmax=255,xohms=150,xmin=200,xmax=3900, ymin=200,ymax=3900
display_rotate=3
#---End-Custom----------------------------------------

I added the command hdmi_force_hotplug = 1, and uncommented above in the file the command config_hdmi_boost = 9 but it still does not work.

Thanks for your help.