Buster locks up OS when running kivy screenmanager app

Start by running the linked screenmanagertest.py reproduction with the reported Kivy setup, then review the linked logs and system details for the Pi 3B+ environment. Trace the graphics-driver behavior associated with the memory growth and compare the reported gpu_mem and Kivy settings. Done means the app can run continuously for days without crashing, locking the OS, or generating errors.

Is this the right place for my bug report?
I was informed by jamesh, Raspberry Pi Engineer & Forum Moderator, to post my reproducible bug at this web address.

Describe the bug
There appears to be a memory leak in the graphics driver used on RPi3B+ and 3B models.

To reproduce
Run the screenmanagertest.py test at the link below.
https://gist.github.com/frankgould/2464c0a3bf4387165d4968f9e849524b

This will require an install of kivy following these instructions:
https://github.com/kivy/kivy/issues/6413

Expected behaviour
The screenmanagertest.py app should run continuously for days without crashing, locking up the OS, or generating errors. In the Actual behavior section below, this bug causes different errors based on parameters set.

Actual behaviour
These are the summary results of the screenmanagertest.py defined above and changing different gpu_mem values and kivy environment values.
https://docs.google.com/document/d/1uX8BVg8FOgBsLm6fnYhFMLib7-EmFjeyz-iQtjutr8k/edit?usp=sharing

System
Copy and paste the results of the raspinfo command in to this section.
fgould@FrankRaspi:~ $ raspinfo
bash: raspinfo: command not found
fgould@FrankRaspi:~ $ sudo apt install raspinfo
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package raspinfo

Alternatively, answer the following questions:

• Which model of Raspberry Pi?
  Pi3B+
• Which OS and version (cat /etc/rpi-issue)?
  Raspberry Pi reference 2019-06-20
  Generated using pi-gen, https://github.com/RPi-Distro/pi-gen, 150e25c4f8123a4c9c63e8dca1b4737fa6c1135c, stage5
• Which firmware version (vcgencmd version)?
  Jun 20 2019 16:12:41
  Copyright (c) 2012 Broadcom
  version a59fb7a74180be0111dbc5c18a37ec6df86f14a3 (clean) (release) (start)
• Which kernel version (uname -a)?
  Linux FrankRaspi 4.19.50-v7+ #896 SMP Thu Jun 20 16:11:44 BST 2019 armv7l GNU/Linux

Logs
https://gist.github.com/frankgould/8ff1a025449290340de356f3ecd7f58a

Additional context
The link below is an original post regarding the graphics driver upgrade plan:
https://www.raspberrypi.org/forums/viewtopic.php?f=66&t=216804