Also tried with version set to 2.1, still not working:

databricks jobs run-now --version 2.1 --job-id 1 --notebook-params '{"key", "value"}'

databricks jobs run-now --version 2.1 --job-id 1 --notebook-params "{"key", "value"}"

databricks jobs run-now --version 2.1 --job-id 1 --notebook-params "{\"key\", \"value\"}"

Error: JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)

Error: Got unexpected extra argument (key, value})

Error: Got unexpected extra argument (key\, \value\})

But the same json string works with Databricks API calls, so I will use the API call directly.