I have attached the output of the commands you requested – I assume you meant on the laptop, i.e. the problematic nxserver host.
Regarding the desktop theme: most settings are identical between the desktop and the laptop (the theme is set to “Breeze” on both machines under System settings -> Workspace Theme -> Look and feel and Desktop Theme; same for Qt widget style under System settings -> Application style -> Widget style). The only thing that differed was the GTK2 and GTK3 themes – I changed them both to Breeze but it didn’t seem to make a difference. So it’s a strange one but if it’s just cosmetic then it’s ok, there must be a different setting I missed.