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Hi PiDanışmanım, Firefox Sync is not designed to be a back up service. The Firefox Sync service takes a copy of the data you wish to include and transfers it to a second device running Firefox. The storage in between devices is both temporary and fragile and is not stable enough to be a reliable backup service. If you have a copy of your Firefox profile for desktop Firefox, you may be able to recover your bookmarks and other data. Please have a read of this [https://support.mozilla.org/en-US/kb/recover-lost-or-missing-bookmarks article]. If you have a copy of your data on a mobile version of Firefox, please follow these [https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer#w_connect-additional-devices-to-sync_ instructions] to connect it to Firefox Sync to copy your data. Lockwise works with local saved login data within an installation of Firefox. You can share that saved login data with other installations of Firefox using Sync. There is centralized storage with Sync because not all data transfers are "real time." However, the data in storage is encrypted within Firefox before transmission, so it is not readable on the server. There is more on Sync here: Sync Client Documentation https://mozilla-services.readthedocs.io/en/latest/sync/overview.html

Note that you should backup your personal data locally and not rely on Sync. *https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles *https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile