What I see:

We open new file descriptor here:

It will be closed by defer:

After we open one more descriptor:

We put him in functions ImportIAMV2(ctx context.Context, contentReader io.ReadCloser) or ImportIAM(ctx context.Context, contentReader io.ReadCloser)

Its takes ReadCloser, but not use Close().

In result second file descriptor is not closed. We can add one more defer f.Close() to handle this case

P.S. or it is closed by another code and I didn't found this =0