This happens because our implementation currently uses AXCoreObject::style() to determine these properties: https://github.com/WebKit/WebKit/blob/34a1f637714c4b88cb27cde64e9c1298a29276d2/Source/WebCore/accessibility/AccessibilityRenderObject.cpp#L1703#L1719 And the style of RenderText seems to be inherited from its parent. This is probably not the correct behavior for macOS (but may be OK for iOS?)
<rdar://problem/108181676>