Apple quietly upgraded the Secure Enclave for older chips in fall 2020
Apple made changes to its A12, A13, and S5 system-on-chips to alter the Secure Enclave in Fall 2020, to include a second-generation model of the Secure Enclave. Whenever Apple introduces new features to its chips, it typically does so as part of a number of other updates included in a new chip release. While unlikely to occur on pre-existing chips normally, it appears that Apple has adjusted some of the designs of its earlier SoCs to make them more secure. MacRumors, a PDF version of the guide includes a table showing the feature summaries of the Secure Enclave, with changes that occurre...
Source: appleinsider.com