why YOLO v3 Keras buggy?

Question

I am running this colab from Roboflow: https://colab.research.google.com/drive/1ByRi9d6_Yzu0nrEKArmLMLuMaZjYfygO#scrollTo=WgHANbxqWJPa

The code should be as-is, but i get errors at the end...

I suspect a TF versioning issue, but how do i know which version of TF i should install instead?

It should use TF1:

%tensorflow_version 1.x

But

!python -c 'import keras; print(keras.version)'

returns: Using TensorFlow backend. 2.2.4

What am i doing wrong here? Unistall TF & reinstall which version?

Thanx Fred