most of my photos are rejected

2.jpg - not well composed, blownout background 

1.jpg - overexposed background. DOF too shallow 

9.jpg - underexposed, not in focus 

I think your f-stop is too narrow - f/2.8 - therefore making the depth of field too narrow.

I also think in all of the photos you need to adjust the exposure to some degree - maybe adjusting the tone curve, using masking etc. The flower pics are a bit too dark.

There are several things that need to be removed:

Also, details are lost in the highlights and your photos need to be sharpened.

Remember, there are millions of flowers in the database so yours must be perfect and stand out.

Here, for instance your first photo after editing. What do you think?

Watch the corners of your assets. This would be a compsosition issue.

The rest of the image is too dark.

Make the dark areas brighter.

1.jpg
The area in focus is too narrow.
Try taking a picture so that a wider area is in focus.

2.jpg
Enlarge the image to 100% and check that it's in focus.

I’ve experienced the same thing. Until now, I still don’t understand the quality standards required by Adobe Stock. Most of the assets I submit always get rejected.