Users with no write access to a record can still see the Edit button on the record detail page when they have the edit permission on the object enabled, either on their profile or through the permission set.
The User will receive the error message below either when they click the Edit button on the record or when they attempt to save any edited data on that record:
"You do not have the level of access necessary to perform the operation you requested. Please contact the owner of the record or your administrator if access is necessary."
This is expected behavior as the actions or buttons on the record are based on the User's object access and not on record access. Even if the User does not have the write record access but has the edit permission on the object level, they are expected to see the Edit button.
For example, a sales rep has Edit permission on Opportunity at the object level but the record is owned by another user with private sharing — the Edit button appears, but saving triggers the access error.
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