cursor flickers, area around cursor not updated

[whitis]

This is on a legally blind user's machine so a larger cursor is needed.

Had problems on problems on ubuntu 20.04 n optiplex 780 with G98 [GeForce 8400 GS Rev. 2] with largest size and Yaru cursor. Cursor was flickering and a square region around the cursor often failed to update.
nvidia-settings -> x screen 0 -> open gl setting enable flip off and quality=high quality helped. Changing cursor in gnome-tweaks appearance themes cursor from Yaru to the smaller redglass helped more. Changing it to DMZ-black steem to help more. But the region around the mouse cursor is still not updated. So, for example, what you type does not appear if it is behind cursor rectangle.

Current state:
   - cursor not flickering
   - area around cursor often not updated.
   - system nearly unusable

Display driver had already been changed from open source to nvidia proprietary to deal with other display update problems.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: nvidia-340 340.108-0ubuntu5.20.04.2
ProcVersionSignature: Ubuntu 5.4.0-107.121-generic 5.4.174
Uname: Linux 5.4.0-107-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.20.11-0ubuntu27.21
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Sun Apr 10 16:06:27 2022
InstallationDate: Installed on 2018-05-05 (1436 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: nvidia-graphics-drivers-340
UpgradeStatus: Upgraded to focal on 2021-05-04 (341 days ago)

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1872870, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.