The trashcan is not displayed if the browser version is less than v1.18.19 which is very old. Prior to this version browser does not support self-delete, so there is no trashcan icon next to such devices.
In your case I doubt you had such old version, but I don’t understand why happens. You can check it at brave://sync-internals/ => Sync Node Browser tab => Device info => choose your device => check MTIME field, it corresponds to the last time when the device was active, and chrome_version field to check the version. This may help to understand why there is no trashcan button.
You can send in DM to me or @Mattches the screenshot of the brave://sync-internals/ page, then we will delete the data from the server, so the theft will not be able to access your data.
Right now we are working on providing ability to wipe the sync data without involving our support team: https://github.com/brave/brave-browser/issues/22884 .