Hi @<1523703107031142400:profile|FlatOctopus65> ! python3.9 introduced a breaking change for codebases that parse code containing slices. You can read more about it here: None . Notable:

* The code that produces a Python code from AST will need to handle indexing with tuples specially (see Tools/parser/unparse.py) because d[(a, b)] is valid syntax (although parenthesis are redundant), but d[(a, b:c)] is not.

What you could do is downgrade to Python 3.8 or use the slice function:
img = img[..., slice(None, None, -1)]
Hope this workaround works for you until we fix this