Why does (improve_contrast:) in config file have apostrophes for true or false?

[18923]

When edited in "Motion Tuner" (improve_contrast:) in config file has apostrophes appended before and after 'true' or 'false'
None of the other true/false options in config file have it.
The config editor flags the line.

motion:
     threshold: 60
     contour_area: 20
     improve_contrast: 'true'
   record:
     enabled: true

[NickM-27]

It's just a product of the ui setting the config value. It would be valid without it as well.