When multiple Gmail accounts are open in the same Chrome profile, the Signitic extension may insert your professional signature into messages from your other accounts, including your personal account.
For administrators
Log in to Signitic.
Go to Settings → Connectors.
Open the Browser Extension connector.
Under “Allow users to disable automatic signature insertion”, to allow users to disable automatic insertion, select “
Allow disabling”.

For users
Once this permission is enabled, open the Signitic extension in your browser and use the option to disable automatic insertion.

This setting allows automatic insertion to be disabled: it is not a filter that automatically excludes personal addresses or domains @gmail.com.