Why slice expression don’t get correct indexes in polars DataFrame?

I have a polars dataframe which looks like this:

Why slice expression don’t get correct indexes in polars DataFrame?

I have a polars dataframe which looks like this:

Why slice expression don’t get correct indexes in polars DataFrame?

I have a polars dataframe which looks like this:

Why slice expression don’t get correct indexes in polars DataFrame?

I have a polars dataframe which looks like this: