You can thank some creative GNOME developers for this dumb change. (Some people may favor this change, and I respect that, but I don't appreciate the change what-so-ever.) Specifically, recently the library known as VTE got changed by somebody in the GNOME project; VTE is a "virtual terminal emulator" library that is an easy way to embed a terminal emulator into an application, and as the MATE Terminal uses this library for convenience, the MATE Terminal was affected.
I'm not a big Debian package expert, despite how I may make myself look; I thus will not explain how to revert to the old version of VTE myself, as I may well give you bad directions (and I don't want to screw something up for you). However, I hope that this topic gets further attention, and that somebody around here with a knack for "holding back" a package of a specific version, such as @Norbert_X, comes along and explains.
In the meantime, my apologies.