When I connect the GPIO expander MCP23008 to the raspberry pi 1 model B+ via I2C, the address of the MCP23008 on the raspberry pi keeps switching between 0x20 and 0x21, and sometimes it's not even detected (see the captions below). What's wrong? How can I stop this uncontrollable change of address on the I2C? The OS is the latest raspberry pi OS desktop version.
Here's the circuit: