Occluded objects overdraw during animations

I have some slide decks in Impress I’ve been using for years that suddenly are having graphics errors during presentations on slides with animations where some graphics objects occlude others. For example, when presenting the only slide in this example presentation, the text of a rectangle behind a foreground object draws on top of the foreground object after an animation step.

To mitigate this, I’ve had to manually break the slide apart into multiple smaller animation steps, which is less than ideal if I need to edit any individual frame.

Version information, in case it helps:

Build ID: 00(Build:2)
CPU threads: 8; OS: Linux 5.11; UI render: default; VCL: gtk3
Locale: en-US (en_US.UTF-8); UI: en-US
Ubuntu package version: 1:7.0.5-0ubuntu0.20.10.1
Calc: threaded

OS information, in case it helps:

Pop!_OS 20.10 on a 64-bit system with X11 as the windowing system and GNOME version 3.38.3,