Thanks Merlino! However this background as we can observe is killing the figure and the colours, because too bright, and it closes the details of the subject on the same way as when you take a picture of someone with a background of the see or bright blue sky ... Actually the reason is that the captors of your caméra is set-up on the global surface of the subject, not focused only to the centre of the subject, here the horseman, and the brightness of the background dominates and closes your diaphragm.
In your dark pictures, you seem to have applied a special filter in your picture, as revealed by lightening the picture = it is an ovale turned to the left at 60°, probably to get rid of the background, table and wall (see right top picture). But it has also killed the colours, because when I brought up light, it required so much highlightening that the colours themselves faded (see middel picture above).
Eric Talmant was also taking his pictiures with an excessive brightness of the background, and no central focus onto the subject, leading to the same dark figures as your second set.
He changed last year the colour and structure of the background, trying several various tones, and effets, and has now a superb compromise and balance between the subject and the background, I put an example of his last pictures borrom left .... Nice job !!
When taking pictures with a smartphone, important is to fingerpoint the subject itself just prior to the picture, to refocus the sharpness to the subject, and the lightening balance optimal to the central subject, not the surrounding. For a camera, use central dots focusing, not general area, as the computer of the camera will average the results of all captors of the total surface and backgrond will dominate this averaging process, not the subjectc.
Sorry for these comments, but the site Putty and Paint also favours dark backgrond and pictures are often badly using general surface focus, darkening the picture and almost 'hiding' the main subject in an unintentional darkness, which to my mind kills in a few seconds the many hoiurs and efforts given to the painting ....