Hi, the message is about services connected to your Firefox/Mozilla Account.

As I understand it, something is changing on the back end related to how you sign in. The method used in Firefox 78 ESR and earlier is being discontinued. That will prevent Firefox 78 ESR from connecting.

As a result, the Sync service will no longer be able to back up your Firefox data or share it with your other Firefox installations (if any). Would this be a problem for you?

Unfortunately, you already have the latest version of Firefox available for your version of MacOS (Firefox Mac OS X 10.9, 10.10 and 10.11 users move to Extended Support Release). So in order to solve this problem with a Firefox update you also need a MacOS update.

Sync is not going be supported with Firefox 78.0 and older anymore. You will need to have 79.0 or later to use Sync on it.

Firefox 116.0 or later requires macOS 10.15 (ten.fifteen) or later. Firefox 79.0 to 115.0 including 115 ESR required at minimum macOS 10.12, 10.13, 10.14 to run.