I figured out the reason:
MySQL connection compatibility error between macOS and Linux.
When I replaced the Database Engine from settings.py: 'ENGINE': 'django.db.backends.mysql' to 'ENGINE': 'mysql.connector.django',
it run completely well.
Maybe its due to mysqlclient build configuration on macOS (especially when using M1/M2 chip)

What you found actually makes sense, especially on newer macOS environments with Apple Silicon (M1/M2).

django.db.backends.mysql usually relies on mysqlclient underneath, and on macOS the build/linking process can sometimes break silently because of differences between:

• Homebrew MySQL libraries
• OpenSSL versions
• ARM architecture compatibility
• Python build environment

I have seen similar cases where:

django.db.utils.OperationalError: (2000, 'Unknown MySQL error')

appears even though:

• the host is reachable
• credentials are correct
• external clients like DataGrip connect successfully

Switching to:

'ENGINE': 'mysql.connector.django'

works because it uses Oracle's pure Python MySQL connector instead of the compiled mysqlclient dependency.

One thing I would also recommend checking is whether mysqlclient was compiled against the correct MySQL client libraries on macOS.

Sometimes reinstalling fixes it:

brew install mysql-client
pip uninstall mysqlclient
pip install mysqlclient

and making sure environment variables like these are set correctly before installation:

export PKG_CONFIG_PATH="$(brew --prefix mysql-client)/lib/pkgconfig"

Also, this line may cause problems depending on DB permissions:

"init_command": "SET GLOBAL max_connections = 1024",

because many remote MySQL users do not have permission to run global configuration commands.

You could try removing it temporarily to rule that out as well.