besides obvious scalability problems in serving high loads ( due to performance, memory etc), another big problem is scalability in the size of the code base, Python is not designed to be a large codebase supporting language with many people working in parallel on the same codebase. I know multiple projects who had to be rewritten from Python to another language both because of performance and code base scalability problems https://stackoverflow.blog/2019/10/07/how-salesforce-converted-einstein-analytics-to-go/

https://getstream.io/blog/switched-python-go/#:~:text=Go%20is%20extremely%20fast.,game%20comparing%20Go%20vs%20Python.