I searched Datasheets of Processor and RAM and other components of RPI4 but couldn't found where it was then I stumbled upon the mentioned above link in a comment that RPI 4 has an SPI-EEPROM so I looked regarding that and found this question where the asker has an issue with boot loading. He mentioned where is EEPROM and also tested it with an Oscilloscope for any ERROR.
This was said by him:
I see two chips near the AV jack that look like two SPI EEPROMs. I can try to hook up the oscilloscope there to see if the ROM is trying to load the EEPROM and what's there. Which one of the two is the bootloader EEPROM? (I assume the one labeled 4H916 064838)
And Here's the Link:
https://www.raspberrypi.org/forums/viewtopic.php?t=253776
Please go through the conversation the RPI moderator/engineer didn't say it is wrong.