this was originally pointed out in a comment on my youtube video here: https://youtu.be/Xf_82stIbB8


here's a reproduction:

1. produce 5000 characters of output: python3 -c 'print("a"*5000)'
2. copy that to the clipboard
3. run this: python3 -c 'import sys; print(len(sys.stdin.read()))'
4. paste
5. press enter
6. ^D

I get the following:

$ python3 -c 'import sys; print(len(sys.stdin.read()))'
...
4096

but I expect the value to be 5001 (+1 for the \n)