Hi @Iniobong Nkanga ,
Hi, there are some details I want to confirm with you:
1, Did this happen after you renamed your domain?
2, Could you please show me how is your tenant sharing settings?
3, Other sites all the same situation? Please check the site sharing settings is anyone with link.
For you references:
https://learn.microsoft.com/en-us/SharePoint/collaboration-options#external-sharing
https://learn.microsoft.com/en-us/sharepoint/turn-external-sharing-on-or-off
https://learn.microsoft.com/en-us/sharepoint/change-external-sharing-site
Please let me know the results at your convenience.
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