Privacy Browser 3.12.2 contains a fix for a problem with WebView’s dark mode on API 29 – 32 (Android 10 – Android 12L) that was introduced with the switch to target API 33 in Privacy Browser 3.12. Initially this was fixed for only API 33 (unless you had a really old and insecure WebView), but this release extends the fix back to API 29. Unfortunately, for reasons that don’t make sense to me, Google has disabled support for WebView’s dark mode on older APIs, so users on API 23 – 28 (Android 6 – Android 9) will no longer be able to force a dark WebView.
As described on the Wikipedia page, API 29 is currently the oldest maintained version of Android. Even though I will continue to release Privacy Browser on older versions of Android as long as it is feasible, this is done on a best-case effort and sometimes there might be features beyond my control that do not work.
From a security perspective, users are encouraged to always use both supported software and hardware. Even if you are using a modified ROM that is attempting to backport security fixes to versions of Android that are no longer supported by Google, if your firmware is not receiving active security patches you are likely vulnerable. For example, in the November 2022 Security Bulletin, there are a number of high severity vulnerabilities in the Android Open Source Project, but the only critical severity vulnerability is in the Qualcomm closed-source firmware.