Hi @john john Pter,
Thank you for posting in this community.
The 400-character limit includes the length of your site name, document library name, folders, and file. It does not count the characters in the domain/tenant name.
For example, if the folder/document URL is
crescent.sharepoint.com/ sites/accounting/Shared Documents/Folder A/Document 123, it only counts the characters highlighted in BOLD above (starting with sites).
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