To add to @Archie’s first point, a lot of AP miners deposited from and withdrew to the same address, which didn’t increase the anonymity set for dedicated Tornado Cash users because these tx are easy to link. You can see a more accurate view of the anonymity sets of the different Tornado Cash Pools on Tutela by using the Tornado Cash Pool Anonymity Auditor.
I’ve written more about this here.
If AP mining were to be reintroduced, it may be worth considering introducing a mechanism to prevent users from depositing and withdrawing to the same address, however, that may complicate some use case formats for users.
I would love to know if this is technically possible if anyone could contribute on that.