When I do not provide users with space access to restrict pages, they are still able to modify their own pages; in this case, I would like users to not have access to edit pages after they are created.

Please add functionality that the permissions can be removed from the owner or transferred to another user.

https://support.atlassian.com/confluence-cloud/docs/assign-space-permissions/#What-the-individual-space-permissions-do

Controls who can edit restrictions on individual pages in your space

If the add/delete restrictions permission is granted to the user or group, they can edit the restrictions dialog on any given page (or blog) in your space, not just their own. Learn more about what page restrictions they can edit.

• They can't edit restrictions on pages that they don't have permission to view.

• Space admins always have this permission, regardless if it is granted or revoked. It's included in the Space Admin permission.

If the add/delete restrictions permission is revoked for the user or group, they can't edit restrictions on any given page in your space.

• If the Add permission under Pages is granted, then they can still edit the restrictions on any page they themselves created.