"To be concerned about" means to feel worried, troubled, or interested in something. It is when you care or think about something because it matters to you. Full definition
Grain - free diets are becoming increasingly popular with dog owners who are concerned about how well their dogs can process their food and efficiently use the energy in their diet. (herepup.com)
If buyers are concerned about how complicated it is to sign up for your app, then suggest how quickly they can do it. (entrepreneur.com)
If there is any concern about something a new puppy gets into, please contact your veterinarian to be certain. (wvrc.com)