Updated Ubuntu Mate has graphics issues

Hi all, I have been using Ubuntu Mate for a year or two and find it great...
most of the time!
I have it installed on 3 laptops, a desktop and a couple of Raspberry Pies.

Since my last apt update and upgrade I am seeing screen tearing on my desktop
and flickering and blacking out firefox on a laptop.

I was having Samba issues and updated all installations. Since then I have
noticed display issues on one laptop and the desktop, I haven't checked the
other installations yet.

I have found work arounds on both the desktop and laptop.

On the desktop simply do the following...

Each time after logging on to Ubuntu Mate I use MATE Tweak to switch to
"Marco (No Compositor)" and then switch back to "Marco (Adaptive Compositor)".

This cures the screen tearing until I log off and on again.
It looks to me like something gets lost when I log off.

Here's some desktop info...

OS: Ubuntu 20.04.2 LTS x86_64
Kernel: 5.4.0-74-generic
Resolution: 1920x1080
WM: Metacity (Marco)
WM Theme: Ambiant-MATE
Theme: Ambiant-MATE [GTK2/3]
Icons: Ambiant-MATE [GTK2/3]
CPU: AMD A8-6600K APU (4) @ 3.900GHz
GPU: AMD ATI Radeon HD 8570D
Memory: 1578MiB / 7144MiB

After the apt update I found firefox unusable on my laptop and had to switch
back to an older version of firefox. (i.e version 89.0 -> 88.0).
Version 89 firefox flickered and blacked out portions of the display.

Here's some laptop info...

OS: Ubuntu 20.04.2 LTS x86_64
Kernel: 5.8.0-55-generic
Resolution: 3840x2160
WM: Metacity (Marco)
WM Theme: Ambiant-MATE
Theme: Ambiant-MATE [GTK2/3]
Icons: Ambiant-MATE [GTK2/3]
CPU: Intel i7-10510U (8) @ 4.900GHz
GPU: Intel UHD Graphics
Memory: 702MiB / 15705MiB

It would appear that the intel graphics drivers do not work well with the latest
firefox, or something like that.

I have work arounds so it is not too inconvenient but do hope these issues
can be resolved.

Any additional info can be provided, just let me know.

Here is a pic of firefox 89 on my laptop.

firefox didn't work on me either with the new update but when i deleted the 20-intel.conf file
that i used to fix screen tearing it started working again, but now i have screen tearing problems.

firefox 88 works and I still have the 20-intel.conf file and no screen tearing.