Two possibilities:
BA's notoriously wobbly IT has sent you an e-mail it shouldn't have (and it wouldn't be the first time), or BA, in their magnanimity have granted you an additional year of Silver without meeting the TP requirements.
In your account, what is the expiry date of your Silver card? If it's 31st August 2023 it's probably the former. If 31st August 2024, you are very lucky