Lower stomach is bulgy and hard 7 years after tummy tuck - is this scar tissue? (photos)

Thank you for your question. Based on your pictures looks like scar tissue. During a tummy tuck specially in that part is not recommend to do liposuction to avoid complication as necrosis after surgery, and months after your tummy tuck you can have liposuction to fix the area. I recommend you to do a physical evaluation with a board certified plastic surgeon for better recommendations in your case.
Best of luck!

Firmness of the soft tissues under your visible abdominoplasty scar is typically caused by one or more of the following: 1. Edema fluid collecting in the soft tissues due to the injury of the operation and interruption of normal lymph flow. This is usually an early finding that corrects itself within the first 6-12 months as lymphatic channels develop across the scar to reach the lymph nodes basins in the right and left groin to drain the fluid.2. Seroma, which is a collection of fluid like a lake between the muscles of your abdominal wall and the soft tissues under the skin. This is typically an early complication that can be managed with a needle and a syringe to aspirate the fluid. 3. Fat necrosis of the tissues under the scar. If the fat at the level of your visible scar was damaged, it will calcify and become firm and sometimes painful
An in person exam will help determine which of the above is contributing to your symptoms. Occasionally, an ultra sound can help increase the accuracy of the diagnosis. Seeing an experienced board certified plastic surgeon is the first step to making the right diagnosis and plan.