iPhone storage being overrun by System Data

I have 128 GB of storage for my iPhone 16 and currently 66 GB of it is being taken up by system data. iOS takes up 19. I have done everything from backing up my photos on a separate cloud to free storage and deleting apps, but no matter what I do my storage fills back up and it messes with my phone's functionality. Messages glitch out, apps won't load, etc. because I only have 1 GB free. I'm seriously at my limit with these and need help on how to clear that System Data because my phone is becoming unusable.