What can be done to fix these issues/depressions after forehead lift? (Photos)

It is obvious that your result is too early to evaluate; a series of before and after photos are needed for such an evaluation. My suggestion would be to wait at least 1 year for result to mature and then address remaining deficiencies and their correction. Hope this helps.

From the photos it appears your surgery was recent. I encourage you to give yourself more time to heal before judging the results. You can consider the appropriate corrections if necessary once you are fully healed. I encourage you to speak to your surgeon about your concerns as she/he is most familiar with the details of your surgery and how you've been progressing through recovery.

It appears from your nicely posted photos. You had a recent forehead lift with the rare complication of areas of denting in the skin subcutaneous tissue. In these cases I have used hyper diluted radiesse/sculptra combination. I recommend at least six vials, syringes. Fee $8000. Best to virtual consult with.