Swelling/edema in feet? If not heart?

My mother aged 50 has swelling in lateral side of both ankles and toes(all fingers) of both feet and fingers of both hands but higher in left side since July 2024.medial side and other parts of both feet are totally normal. When we press swelling of ankle there is almost immediate bounce back and no much indentation. Kft lft cbc tests are normal . She hasn't been tested for heart like ECG ECHO recently though. In 2023 january ECG,ECHO were normal(after that not tested) Left side has higher swelling than right What you think can be causes? Can this type of swelling in fingers and lateral ankle be heart related or it effects all foot rather than only this?? What can be other cause if not heart?? Kft is normal. Thyroid tests normal.(T3,T4,TSH) Though anti tpo littlebit high (possibly hashimotos)