Web placeholder text uses TextColour instead of the default placeholder colour

In web projects, the PlaceholderText of text-entry controls is drawn using the control's TextColour instead of the standard muted placeholder colour. Any project that sets a custom TextColour on a TextField, TextArea, SearchField, NumericTextField, ComboBox, DateTimePicker, or TagField gets a placeholder that looks like entered text (for example, a bright orange hint), both in the running web app and in the Studio web page designer preview.

Expected behaviour: as on desktop, placeholder text should always render in the default placeholder colour regardless of TextColour. TextColour should affect typed text only. Placeholder text is chrome, not content.