Most of the photos taken with the same camera were allowed last year. However, since some time ago, all the photos I post are not allowed.
Exposure of highlights and shadows is an issue in all of the photos.
Unfortunately, there are quite a number of issues with your submissions. Quality standards have increased over the last few years.
Problems that I can see that affect quality are:
The following links may be useful.
It's not the camera, even that with a better camera you may get less refusals, but the picture. Each picture is vetted individually, and the moderators do not look the camera or your settings, but analyze only your pictures.