Should the layout of Android's "secure keyboard" be localized?

Some application use the "secure keyboard" of my ColorOS 12.1 (Android 12 customized by Oppo). While my device is configured to use German language, the keyboard displayed in such apps uses the English QWERTY layout, and even worse: I'm not offered any diacritical characters when long-pressing a key. That makes it rather useless for German. So I wonder: *Is this a security feature, or is it a bug?*