This Button is for changing between Full Screen Mode and the default normal Window Mode. That is normal Behavior. For minimize it in the Taskbar is the Button left from it.
P.S.: You can set up a default Size if You want. For this, go to the Terminal Settings:
My window size gets progressively smaller every time I click it to go from full screen back to "default size". Even if I F11 full screen, F11 "default size" a couple of times, it starts shrinking.
It doesn't affect me at all because I use Super to position things anyway. It's just something I happened to notice yesterday. But my settings look the same as yours, so as Storm mentioned, it might just be a bug and probably only affects some systems.
EDIT: Just checked and it doesn't happen in a Wayland session.
Interesting. So, it is a Xorg Problem. Normally we write here, that something is a Wayland Issue. There comes this so unexpected, hahaha!
But can You manually expand the Terminal Window? I mean, when You go with the Mouse Cursor to the Edge of the Window and then get the Icon for changing the Size.
weird , i'm on Lite (so Xorg) , and my terminal window behaves normal whatever i do with it ...
minimise , maximise , shrinks/expands by dragging borders , and opening after i closed it , to normal size I've set in preferences
( Xfce terminal )
I don't think so, but my screen scaling in display says %100.
I screen recorded it in action for the curious. But I wasn't sure where besides Youtube I could upload it to share. For now I uploaded it on a blog to put a link here. It won't play in my browser so I don't think it shows if you use an adblocker.
The toggle is turned off. Also using a new profile or resetting that profile does not change the behavior.
I missed that. Yes I can drag the window into a new size. Then it will still shrink as before if I use the button to fullsize/default size it or F11.
If I use Super Left/Right it will anchor it to the left or right half of my screen and fullsize/default with F11 will work as expected (full screen/half screen) but using the button to fullscreen and then unfullscreen it will cause it to shrink again. Which can be solved by Super Left/Right again to reset it to fill half the screen. But using Super Up (full screen) Super Down (default size) causes it to shrink.
It doesn't effect me much because I usually use it either at the default size it opens to or sized to half screen.
Oh my gosh, I just followed your advice and I expected resolution. But it was still shrinking. So I rebooted the pc and tried - still shrinking!
I'm getting ready to leave for work now, but when I get home I'm going to turn on my other pc and see if the terminal shrinks there too or just this one.
In a bizarre turn of events, the terminal on my other computer Zorin 17.2 Core install behaves the exact same way, shrinking in Xorg (but not Wayland). I probably did use the same bootable media to install, but I do checksums when I download things. I'm at a loss, especially as no one else's terminal seems to exhibit this inexplicable behavior.
When I noticed the terminal did that, I tried a few other programs because I wondered if they all did that. But nothing else I tried (so far) had the same shrinking behavior.
I see there is another terminal called XTerm on this computer that is not on my other Zorin computer. This probably came with herbstluftwm which I have recently added to this computer but not yet to the other computer (I have been working on this pc a lot more lately since the room is warmer and cozy). I did try with XTerm just now and it does not shrink, but ugh the font is almost unreadable.
I gave them a quick try just now and Black Box seems a little slow in start up, and is not as well polished as Ptyxis, which also happens to have a lot more customization, in terms of appearance at least, including my favorite palette: Catppuccin.
Although unfortunately they're both quite heavy on resources: ~250Mb and 500Mb of RAM, respectively. Compared to the ~50Mb of Gnome Terminal, that's quite a difference.
I'm currently using Alacritty myself which uses about ~90Mb.
As far as I understand this, both were Candidates to replace the old Gnome Terminal in a future Gnome Version. On Fedora is Ptyxis already as Terminal preinstalled. BlackBox is since a Year without an Update. So, maybe the Support has stopped there(?)
The higher RAM Consumption could come because there are Flatpaks maybe.
Alacritty I didn't tried. I saw a couple of Videos about it. I lokked interesting. But the thing with the manual Customization is something ... that is nice but I would need time to built it up, hahaha!
I saw some Videos about Ghostty, which looks nice, too.