vcard birthday format not valid

I use emClient on Windows and Thunderbird with Cardbook addon on Linux.
emClient generate Birthday-Entrys like BDAY;VALUE=date-time:2019-02-18T00:00:00

After sync I can ́t edit the contact in Cardbook. I got an Error because the birthday format doesn ́t match.

Cardbook knows two formats vCard4 with YYMMDD  or vCard3 with YYYY-MM-DD.

https://en.wikipedia.org/wiki/VCard#Properties

How can I do to sync and use both programs?