https://www.androidpolice.com/android-13-blocks-accessibility-services-sideloaded-apps/

It just takes an additional warning acknowledgement.

Google isn’t fully stopping sideloaded apps from using accessibility services, though. Once you’ve run into the dialog saying that accessibility services are restricted for the app in question, you can activate access under the app info screen in the top right corner via the “allow restricted settings” menu entry, so if you’re a power user interested in augmenting your phone with a legitimate app, you can still do that. This seems like a loophole that nefarious apps could circumvent by instructing users to enable restricted settings. Thus, it’s possible that Google will still change this behavior before going live with stable Android 13.