Ubuntu 20.04 switches monitor positions each time I unlock

I'm running 20.04 on a laptop that alternates between two monitor configurations

• at the office the laptop is connected to two external monitors via usb-c, the first monitor (HP EliteDisplay E243d) has an integrated docking station and the second monitor (HP EliteDisplay E243) is daisy-chained to the first.
• at home the laptop is connected to a single monitor, identical to the one at the Office (HP EliteDisplay E243d)

Nowadays I work almost exclusively at home and the Linux keeps messing with the monitor arrangement: on boot everything is fine, linux "remembers" that I want the monitor as primary (on the right) and the laptop screen as secondary (on the left). If I leave the desk for enough time the screen locks and two things happen when I come back:

• Lock screen (GDM?) still has the screens in the right order
• I enter the password and the screens rearrange: the monitor is now on the left and no longer the primary, laptop screen is on the right and primary... and the two have a gap in the middle where the third monitor used to be when I was at the office

I suspect there must be some kind of saved configuration, but I have no idea where to look. Any suggestions?