On Android 4.x MapBoxGL map is blank - wrong SSL picked up

I have an app that uses MapBoxGL for rendering a map. It works on a recent Android phone. But on an old Android 4.4 phone, the map is not shown (just a white screen).

I can see some SSL errors in the log output. I do package openssl 1.0.2p in the apk. But using QSslSocket::sslLibraryVersionString() I can see, that 1.0.2e is used.

Old Android versions did ship with libssl (I guess 1.0.2e). So I guess, that QSslSocket uses the old outdated version from the system instead of the newer one in the apk. Newer Android versions don't ship with libssl, so mine is used.

Qt 5.11.3 works fine.