Bug: luksClose search LUKS header but it is detached

Hi all,

I noticed that cryptsetup LUKS extensions is searching for a LUKS
header in the device.
This is expected when the LUKS header should be in the device.
But I used a detached LUKS header, so I wasn't expecting to see
cryptsetup searching for the LUKS header in the device.

You can see that in the log file "log.txt" - in the URL:
https://drive.google.com/file/d/1DcrpklgE75oE5znAxHAlp9CPikkYbVq1/view?usp=sharing

You may notice that I used a "--header" flag, but I also tried without
it - still, cryptsetup behaved the same.

The incriminating lines from the attached log are as follows:
"
# Trying to read primary LUKS2 header at offset 0x0.
# Opening locked device /dev/sdb1
# Verifying locked device handle (bdev)
# Trying to read secondary LUKS2 header at offset 0x4000.
# Reusing open ro fd on device /dev/sdb1
# Trying to read secondary LUKS2 header at offset 0x8000.
# Reusing open ro fd on device /dev/sdb1
# Trying to read secondary LUKS2 header at offset 0x10000.
# Reusing open ro fd on device /dev/sdb1
# Trying to read secondary LUKS2 header at offset 0x20000.
# Reusing open ro fd on device /dev/sdb1
# Trying to read secondary LUKS2 header at offset 0x40000.
# Reusing open ro fd on device /dev/sdb1
# Trying to read secondary LUKS2 header at offset 0x80000.
# Reusing open ro fd on device /dev/sdb1
# Trying to read secondary LUKS2 header at offset 0x100000.
# Reusing open ro fd on device /dev/sdb1
# Trying to read secondary LUKS2 header at offset 0x200000.
# Reusing open ro fd on device /dev/sdb1
# Trying to read secondary LUKS2 header at offset 0x400000.
# Reusing open ro fd on device /dev/sdb1
# LUKS2 header read failed (-22).
"

Do you consider it to be a bug?

Best Regards,
David.