Text intersects its shadow; both are visible when fading

Discovered while testing MC-108323.

The bug

Text shadows are rendered underneath text, which usually occludes them, but the full shadow ends up being visible as text fades.

How to reproduce

1. /title @a title {"text":"■"}

2. Observe as it disappears

Expected results

Only the normally visible areas of the shadow would be seen when the text fades.

Actual results

As it begins to fade, the rest of the shadow is revealed.