I want to know why i get two Content-Transfer-Encoding in email test but i put only one in my header and DKIM-Signature also got one

Here is an example from the Yahoo Mail source.

yahoo email source

I'm encountering an issue where my email headers include a duplicate Content-Transfer-Encoding: quoted-printable entry. The duplicate seems to appear after the DKIM signature is applied, and I want to prevent this from happening.

Is there a way to configure DKIM (or the email headers) to avoid generating this last Content-Transfer-Encoding header? Alternatively, can DKIM be set up to ignore specific headers during the signing process? I find this behavior strange and would appreciate any guidance or insights on how to address it.