Google Support:
Hey Everyone,
Starting in early 2025, Chrome Sync (using and saving data in your Google Account) will stop working on versions of Chrome that are more than four years old. If you are on a version of Chrome that is older than four years old, you may begin to see the error message “Update Chrome to start sync” or "Update Chrome to keep using the Chrome data in your Google Account”.
To continue to use Chrome Sync, please update your browser to the newest Chrome version that is available on your device. If you are unable to update your Browser to a version that is less than four years old, you will not be able to use the Chrome Sync feature on that device any longer.
As always, please feel free to send us feedback using these instructions.
Rebecca, Chrome Support Manager
Details
Sign-In and Sync
Source: