UNKNOWN ROOT WINDOW TYPE DETECTED (Nemo-desktop), please file a bug

[dwedia]

I am getting this error when trying to restore wallpaper settings with Nitrogen, on Linux Mint 20.3 Edge edition.
It restored the wallpaper on screen 3, but not the other two. What could cause this?

ramiraz@Thor ~> nitrogen --restore
UNKNOWN ROOT WINDOW TYPE DETECTED (Nemo-desktop), please file a bug
UNKNOWN ROOT WINDOW TYPE DETECTED (Nemo-desktop), please file a bug
UNKNOWN ROOT WINDOW TYPE DETECTED (Nemo-desktop), please file a bug
WARNING: More than one Desktop window found:
0x 360000f 3Nemo-desktop
0x 360000b 3Nemo-desktop
0x 3600003 3Nemo-desktop

ramiraz@Thor:$ uname -a
Linux Thor 5.15.0-33-generic #3420.04.1-Ubuntu SMP Thu May 19 15:51:16 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux