Edit access to a file that has been shared with you as view-only

In Nextcloud, someone is sharing an Excel file with me that I only have view-only access to. However, when I open the file in explorer.exe, I receive no message, and I am even allowed to edit the file. How is this happening?

read-only share doesnโ€™t apply internally inside the doc it only applies to Nextcloud file access. once the file is synced locally or downloaded this file could be edited locally but the user can not upload them and update initial file.

Thank you for your response. Your reasoning is correct. However, with the view-only access I provided through the Nextcloud application, I could edit the file locally, and the changes were also reflected for the file owner. After several attempts, I realized that I had configured the sharing settings on my Nextcloud web platform account so that, by default, individuals could create and modify access. I believe this is why the view-only access was not being enforced.