Added support for immutable backups using Google Cloud Storage.
Added a "Recover" button for storage locations that support immutable backups. Clicking "Recover" causes Arq to scan the backup set and attempt to recover all objects that have been "deleted" ("delete marker" created in S3, or "live" item deleted in Google Cloud Storage).
Enabled periodic back-up-and-validate for pCloud backup plans.
Improvements
Updated MimeKit from 4.15.0 to 4.15.1 which has a security fix.
When editing a backup plan, if "Include" is selected for network interfaces (or WiFi networks) but the list is empty, Arq now shows a warning before saving.
Updated the encryption-password prompt to remind users to save the password in a password manager.
Added a "Learn More" link when object lock is not available for the chosen storage location.
