Fix scaled flatpak application (nextcloud client)

I run the Nextcloud client in Linux Mint 20.3

Guys, I noticed a link with an available update on my Nextcloud desktop client app, so i went for it and downloaded the official appimage so i ended up with 2 stances of nextcloud running at the same time, then i removed the old one leaving only the appimage. With the appimage, icons to launch Nextcloud are not setup and i did not like the idea of having to keep it in my downloads folder, so i ended up removing it. I ALSO had the same scaling issue with the appimage described below.
Then i searched for it in Mint’s software manager, and downloaded it as a Flatpak. So now i have it installed, version 3.8.1

The problem now, (besides that it is trying to resync my 95GBs of data ) is that the GUI is scaled big and it goes off the screen so i can not reach the buttons at the bottom of it, rendering the application unusable.

Reading some docs i found a way to set the scaling factor for flatpaks like this in my case:

sudo flatpak override --env=GTK_CSD=0 --env=GDK_SCALE=1 com.nextcloud.desktopclient.nextcloud

So the result:

sudo flatpak info --show-permissions com.nextcloud.desktopclient.nextcloud
[Context]
shared=network;ipc;
sockets=x11;wayland;
devices=dri;
filesystems=xdg-run/Nextcloud:create;xdg-config/kdeglobals:ro;host;

[Session Bus Policy]
com.canonical.AppMenu.Registrar=talk
org.kde.kconfig.notify=talk
org.kde.KGlobalSettings=talk
org.kde.StatusNotifierWatcher=talk
org.freedesktop.Notifications=talk
org.freedesktop.secrets=talk
org.kde.*=own

[Environment]
TMPDIR=/var/tmp
GDK_SCALE=1
GTK_CSD=0

I exit the client and re launch it, to no avail… it keeps showing huge.
I also tried GDK_SCALE=0.5 but no joy either…
Do you know any other tricks i could try to make it look normal?
My display settings are normal, i am using no scaling and i tried disconnecting my external monitor and i get the same problem in my laptop’s native monitor at 1920x1080 resolution

I found another way that is supposed to work but so far still the same issue:

flatpak run --command=sh com.nextcloud.desktopclient.nextcloud

Enters into a root terminal in the nextcloud application, then i tried:

root@thebox:~# flatpak run --command=sh com.nextcloud.desktopclient.nextcloud
[📦 com.nextcloud.desktopclient.nextcloud ~]# env | grep GTK_THEME
[📦 com.nextcloud.desktopclient.nextcloud ~]# export GTK_THEME=Mint-Y
[📦 com.nextcloud.desktopclient.nextcloud ~]# env | grep GTK_THEME
GTK_THEME=Mint-Y
[📦 com.nextcloud.desktopclient.nextcloud ~]# export GTK_THEME=cinnamon
[📦 com.nextcloud.desktopclient.nextcloud ~]# env | grep GTK_THEME`

Still no go…

Any other ideas?
Thank you!
Screenshot showing the issue:

System information:

$inxi -Fzxxx
System:    Kernel: 5.15.0-69-generic x86_64 bits: 64 compiler: N/A Desktop: Cinnamon 5.2.7 wm: muffin 5.2.1 
           dm: LightDM 1.30.0 Distro: Linux Mint 20.3 Una base: Ubuntu 20.04 focal 
Machine:   Type: Laptop System: LENOVO product: 20L70025US v: ThinkPad T480s serial: <filter> Chassis: type: 10 

CPU:       Topology: Quad Core model: Intel Core i7-8650U bits: 64 type: MT MCP arch: Kaby Lake rev: A 
           L2 cache: 8192 KiB 
           flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 33599 
           Speed: 800 MHz min/max: 400/4200 MHz Core speeds (MHz): 1: 800 2: 800 3: 800 4: 800 5: 800 6: 797 7: 800 
           8: 800 
Graphics:  Device-1: Intel UHD Graphics 620 vendor: Lenovo driver: i915 v: kernel bus ID: 00:02.0 chip ID: 8086:5917 
           Display: x11 server: X.Org 1.20.13 driver: modesetting unloaded: fbdev,vesa resolution: 1920x1080~60Hz 
           OpenGL: renderer: Mesa Intel UHD Graphics 620 (KBL GT2) v: 4.6 Mesa 21.2.6 direct render: Yes 
Audio:     Device-1: Intel Sunrise Point-LP HD Audio vendor: Lenovo driver: snd_hda_intel v: kernel 
Info:      Processes: 339 Uptime: 39m Memory: 23.23 GiB used: 3.00 GiB (12.9%) Init: systemd v: 245 runlevel: 5 
           Compilers: gcc: 9.4.0 alt: 9 Shell: bash v: 5.0.17 running in: terminator inxi: 3.0.38 

and:

xrandr
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384
eDP-1 connected (normal left inverted right x axis y axis)
   1920x1080     60.01 +  60.01    59.97    59.96    59.93  
   1680x1050     59.95    59.88  
   1600x1024     60.17  
   1400x1050     59.98  
   1600x900      59.99    59.94    59.95    59.82  
   1280x1024     60.02  
   1440x900      59.89  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1440x810      60.00    59.97  
   1368x768      59.88    59.85  
   1360x768      59.80    59.96  
   1280x800      59.99    59.97    59.81    59.91  
   1152x864      60.00  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   800x512       60.17  
   700x525       59.98  
   800x450       59.95    59.82  
   640x512       60.02  
   720x450       59.89  
   700x450       59.96    59.88  
   640x480       60.00    59.94  
   720x405       59.51    58.99  
   684x384       59.88    59.85  
   680x384       59.80    59.96  
   640x400       59.88    59.98  
   576x432       60.06  
   640x360       59.86    59.83    59.84    59.32  
   512x384       60.00  
   512x288       60.00    59.92  
   480x270       59.63    59.82  
   400x300       60.32    56.34  
   432x243       59.92    59.57  
   320x240       60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 160mm x 90mm
   1920x1080     60.00*+  50.00    59.94    30.00    25.00    24.00    29.97    23.98  
   1920x1080i    60.00    50.00    59.94  
   1680x1050     59.88  
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1366x768      59.79  
   1280x800      59.91  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    70.07    60.00  
   832x624       74.55  
   800x600       72.19    75.00    60.32  
   720x576       50.00  
   720x576i      50.00  
   720x480       60.00    59.94  
   720x480i      60.00    59.94  
   640x480       75.00    72.81    66.67    60.00    59.94  
   720x400       70.08  

Got it fixed with:

flatpak override --env=QT_SCALE_FACTOR=0.5 com.nextcloud.desktopclient.nextcloud