Encryption is a method of protecting data's confidentiality. When data is encrypted, it becomes unreadable to any unauthorized persons who get access to it.
All notifications are encrypted on Fitbit Versa and Fitbit Ionic. If you have a different Fitbit device paired to your Android phone, you can require that only encrypted notifications pass from the phone to your Fitbit device. For instructions, see How do I get notifications from my phone on my Fitbit device? If you choose not to use this setting, your Android phone attempts to send notifications with encryption, but if encryption fails, the notification will be sent unencrypted.
Note that unencrypted in this context means only that the text visible on your Fitbit device is potentially vulnerable to an eavesdropping device. So, a person attempting to intercept Bluetooth transmissions might see the contents of the message, or if you received a call notification, the phone number. Your personal information stored with Fitbit is always encrypted.
Be sure to update your watch to the latest version of Fitbit OS. For more information, see How do I update my Fitbit device?