I've had this issue for a while and I can't get rid of it.
In screenshot 1, the selected layer slices correctly with one outer wall at 0.4mm thickness and one long line as inner walls.
In shot 2, it slices incorrectly with a lot of zigzags making the print unusable. It even puts holes in the print.
Designed this testpiece for different widths and back in Cura 3.5 och 3.4 I belive, it was wlicing fine.
Tried changing line width and nozzle size and Compensate Wall overlaps, and all other settings.
I've attached the generated gcode, stl, and Fusion360 file.
ClasOhlson_PLA.stl CFFFP_ClasOhlson_PLA.gcode Filament Test v14.zip