Based on the information you’ve provided, it seems that the versions of TensorFlow and TensorFlow.js that you are using are not compatible with each other. It’s recommended to use TensorFlow 2.2.0 and TensorFlow.js 2.4.0 or later version.
In addition to that, I would suggest you to check if the architecture of the model and the input preprocessing is compatible with the converter, and if not, try modifying the architecture or the input preprocessing of the model to make it compatible with the converter.
You might also want to check if there are any newer versions of the packages you are using to see if that fixes the issue.
Finally, you could try using the tfjs.converters.save_keras_model function in TensorFlow 2.4 or above to convert the model instead of tensorflowjs_converter, it should work better.
Please, tell me if some of this suggestions works for you.
Regards