Contact sharing settings have grant access using hierarchies unchecked

Configuring one app per department and activating record pages for each app will ensure that users view records in a way that makes sense for each department. An app is a collection of items that work together to serve a particular function. An app can have different record pages for different objects and profiles. By activating record pages for each app, the administrator can customize what users see based on their app context. Reference: https://help.salesforce.com/s/articleView?id=sf.app_manager_overview.htm&type=5 https://help.salesforce.com/s/articleView?id=sf.app_builder_customize_lex_pages_assign.htm&type=5

The Setup Audit Trail is a tool that allows you to view and download a log of changes made in your org's Setup area. The log shows up to 20 fields of information for each change, such as who made it, when it was made, what type of change it was, and what values were changed. You can use the Setup Audit Trail to track configuration changes directly in production and identify any unauthorized or problematic changes. One of the changes that the Setup Audit Trail tracks is when a user's profile is changed and who changed it. This means that you can use the Setup Audit Trail to see when a user's profile has been changed and who changed the data. Reference: https://help.salesforce.com/s/articleView?id=sf.monitorsetup.htm&type=5