Explanation
Report folders are used to organize and secure reports in Salesforce. You can set different levels of access for different users or groups on each report folder. To preserve the integrity of the source reports for dashboards, you can create a new report folder with viewer access only and move the dashboard reports to that folder. This way, users can view the reports but not edit them. References:
https://help.salesforce.com/s/articleView?id=sf.reports_folders.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.reports_dashboard_folder_access.htm&type=5