I really love Mate, I installed it on my old MacBookPro and on my Asus Laptop
But on both computers Chrome, yes only Chrome, have this behaviour which really annoyed me.
I don't really know how to mention it but
I installed google-chrome-stable from PPA
then it has 2 title bar like this, maximizes or in a windows mode it doesn't matter
My theme is Ambiant-MATE
my font is Ubuntu Regular 11
than Windows title font: Ubuntu Medium 11
and Fixed width font: Ubuntu Mono Regular 13
My Mate Panel is Familiar
I use Marco without a compositor
it is on Ubuntu 20.04LTS installed from ubuntu-mate-20.04.1-desktop-amd64.iso
Ironically today, when I came to follow up, the issue disappears, probably due to an update because Thursday night I installed zoom and did my update. Now Google Chrome version is 85.0.4183.102 instead of 85.0.4183.83
CSD is like how you have tabs in the title bar there should be a way to disable that you can in firefox I didn't even know csd was an option for chrome