Some problems with this particular system:

If the TPM signs the original image taken by the camera, then even the slightest image processing on another device would invalidate the signature. Routine changes like cropping, scaling, converting between image formats / quality levels, or applying image filters would invalidate the signature.

An adversary can manipulate the date/time settings on the camera and forge evidence to frame someone. "This cryptographically signed photo, with timestamp, proves that you were here at this time!"

And camera sensors can get damaged and need replacement. But if replacement of the TPM-and-sensor chip is allowed, then you can just as well replace it with a sensor from another camera. In which case a signature from a specific TPM+sensor doesn't prove that a specific camera took the photo, at best it might be evidence that a specific camera model took the photo.

If the manufacturer will happily ship a replacement TPM+sensor for a specific camera, someone can fraudulently claim that their sensor is broken and be given a new TPM+sensor for the same camera. And there will now be multiple TPM+sensors in existence that have the same key. Since this module can be switched between cameras, there could be multiple cameras that signed a given picture.

To ship (identical) replacement TPMs, the manufacturer would also need to know the private keys of all the cameras, so the manufacturer could forge arbitrary signatures at will.

Finally maybe the manufacturer doesn't want to deal with the above problems and decides that repairing the camera's TPM is not allowed after all, or that only the manufacturer is allowed to repair a camera, but then they may be in violation of right-to-repair laws in several jurisdictions.