Akonadi > Agent Google Groupware behavior 2-factor-authentification

[Herbert <ein_freund@hotmail.com>]

I run KDE/Plasma on Debian 11 and use PIM-Suite 'kontact' since a long time.
My google-account is embedded via akonadi-agent google-groupware which 
performs well i.e. to have acces to calendar / dates / contacts.
Well the contacts module in pim-kontact (kaddressbook) did not have my 
attention over the last time ... But now I state following behavior:
WHEN I define in my google-account under security the 2-factor-authentification 
it seems to influence data-verification of my google-contacts within 
kaddressbook --> only a few contacts are shown.
Stopping 2-factor-authentification leads to correct behavior = all my google-
contacts are shown in kaddressbook.
Is that an issue in akonadi-agent google-groupware ?
Beware that 2-factor-auth. has no effect on google-calendar and google-lists

Greetings
Herbert S.