Window shrinks on switching focus

[Smylers]

MATE Terminal windows shrink themselves every time they lose or gain focus, when CSD is enabled.
This screen recording demonstrates the problem: https://imgur.com/a/kLZYUgh

GTK_CSD=1 in the environment. Running MATE Terminal by any means (the screen recording uses Alt+F2) initially appears to work fine, but whenever focus is switched to another window (with either the mouse or Alt+Tab) the MATE Terminal window shrinks slightly. Then slightly more when it regains focus.

The video shows GNOME Terminal being run as the other window; it retains its size. But the other application can be anything at all.

This doesn't happen with GTK_CSD=0; MATE Terminal windows then leave their size alone.

The shrinking behaviour started happening since I upgraded to Ubuntu 20.04 LTS, from 18.04 LTS. The mate-terminal package is version 1.24.0-2ubuntu1.

To demonstrate the problem and eliminate config in my account being the problem, I created a new account to check the bug exists there (it does) and record the video. The computer has the gtk3-nocsd package installed, but in /etc/X11/Xsession.d/01gtk3-nocsd there is the line:

  export GTK_CSD=1

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Geert Uytterhoeven (geert-linux-m68k)]

I started seeing this bad behavior after upgrading from Ubuntu 20.04 LTS to 22.04.1 LTS.
GTK_CSD is unset. Setting it to 0 (or 1) does not make a difference.
The upgrade to 22.04.1 LTS switched from Xorg to Wayland.
Disabling Wayland (set WaylandEnable=false in /etc/gdm3/custom.conf) fixes the issue.

mate-terminal version: 1.26.0-1ubuntu2