Loss of information when converting RAW to DNG

Hello. My question to developers of DNG concerns the DNG format, into which I have been converting all RAW photos, considering that DNG is a complete analogue of RAW. I use Canon equipment.

1. I recently learned that in many photo contests, if a photo reaches the final and claims prizes, confirmation of the rights to this photo (authorship) in the form of RAW files is required, and the DNG format is not considered as such.

2. Once I had a claim about a Canon lens purchased - on specific photos as an example. The support required me to submit RAW files. The DNG files were not accepted by Canon support and I was told that they lacked some important information.

Question 1. Please confirm that when converting RAW to DNG some information is lost, that

a) does not allow to identify the authorship of the photo,

b) does not allow to perform photo equipment service support.

Please indicate which information is being lost.

If the statements written above are incorrect, please give a professional refutation.

Question 2. What recommendations can you give to avoid the problems described above when using DNG?

I believe that these issues are very important for many photographers around the world.

Thank you!