If the passport linked to your UK ETA has expired or changed, your existing UK ETA cannot be used.
A UK ETA is linked to the passport used in the application.
Therefore, if your passport expires or you receive a new passport, you must apply for a new UK ETA using your new passport details.
A UK ETA is generally valid for 2 years, but if the linked passport expires earlier, the UK ETA also expires with that passport.
This means that even if the original UK ETA approval period remains, you cannot use it with a new or different passport.
Before traveling, make sure your passport number, passport expiry date, and UK ETA approval information match the passport you will actually use for travel.