Dither for decoding any JPEG file

[SUGHuser]

Hi )
I use XnView MP latest version https://www.xnview.com/ , I known what theee used JPEG LI encoder and decoder , how much I known , there use MOZJPEG or JPEGLI for reading / decoding JPEG files , but have problem , very big problem....

This is original sample , crop from camera

This is Floyd steinberg dither in XnConvert 1.104

This is ACDSee Pro sample

as you can see , in ACDSSee Pro 5.0 with IDE_ACDstd 5.0.56.0000 gradient quality highest and absent rude colors.
please create dither in JPEGLI decoder with quality as in ACDSee Pro 5.0

[wwinniww]

In which cases does dithering make sense?
I doubt it would be of benefit for JPEG files with RGB or XYB color profile, it can be useful for JPEG files with subsampled color channels.

[SUGHuser]

This be if read photos from smartphone ) in standard smartphone all write as:
Subsampling 2x2,1x1,1x1
or
Subsampling 1x1,2x2,1x1
or
Subsampling 2x2,2x2,1x1
or
Subsampling 2x2,2x2,2x2
if write as
Subsampling 1x1,1x1,1x1
dithering not need , but in other causes , need do dithering
at least as option
I sayd about STANDARD JPEG file , NOT JPEG Li , because I want increase read quality in standard JPEG file from smartphone need do ditherning gradients