The Excluded Domains list only does two things:
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Prevents Bitwarden from prompting you to save passwords (if you have enabled the option “Ask to add/update existing login”).
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Prevents Bitwarden from prompting you to save or use passkeys (if you have enabled the option “Ask to save and use passkeys”).
If you want to prevent Bitwarden’s inline auto-fill icon from appearing, you go to Settings > Auto-fill and set the value of the option “Show auto-fill menu on form fields” to “Off”.
If you want auto-filling to work on some login pages and not on other pages, then you should go to the login page, use the Auto-fill and Save button to capture the login page URI, and then edit the vault item to remove other URIs, and to customize the URI match detection method to suit your purpose (by clicking the 
icon to the right of the stored login page URI).