Excluding certain SharePoint sites from search would mean the contents from the excluded sites won’t be available to M365 tenant search and Copilot for M365 using Restricted SharePoint Search feature. The downsides using this feature are: Limited Findability: By excluding certain SharePoint sites from search, you limit the findability of data. Users would need to know the specific sites where the data resides in order to search for it. This can hinder efficient data retrieval and records management.