Date in git-commit output inconsistent with log.date format

I was amending a commit message, and noticed the date in the output is printed in 'default' format, as shown below:

$ git commit --amend --no-edit
[x bf63ada92] Test commit
 Date: Mon May 16 14:25:57 2022 +0200
 1 file changed, 32 insertions(+)
 create mode 100644 test.txt

Since I have set log.date=iso, I was expecting the date to use the format defined in that configuration. Is it intentional that the default format is applied instead ?

Thanks Damien

PS: Apologies if this has been asked before, I did search the list
archive without finding anything relevant.