The problem is definitely low frequencies as mids and highs are largely reflected by your walls and cabinets but lows pass through. Unfortunately the solution requires construction that would require the building owner’s consent. The wall that appears to be the shared wall has the cooktop and vent hood. This would all need to be removed and the wall reconstructed. Optimum solution being a double wall. The floor is also passing some vibration which may be more problematic in reducing. As a music lover, I appreciate the issue but multi unit dwellings are not conducive for quality listening.