raspberry pi – Experiencing issues with reading data from a UART connection (garbage)

I have two Raspberry Pi 3 units and require them to exchange data via uart connection (/dev/serial0). Although I accomplished this task successfully approximately two months ago, I now encounter an issue where executing my codes results in receiving only garbage data on both ends of the connection. The connectors are newly acquired, and the power supply output remains stable at 5V.

RP3-1:

RP3-2:

boot/firmware/config.txt
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boot/firmware/cmdline.txt
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I attempted various tests , including replacing the connectors and power supply. Additionally, I conducted tests on a Raspberry Pi 4 Model B to isolate the issue.

RP4 -> 1-RP3 = succesfull
RP4 -> 2-RP3 = succesfull
1-RP3 -> 2-RP3 = garbage
2-RP3 -> 1-RP3 = garbage

Also, I tried to use minicom, but output was the same.
minicom output