That seems odd. I have upgraded (other than Firefox, since the new version has problems with outlook.office.com) and have all of those in place -
apt list --installed | grep -E "akonadiconsole|akregator|kde-standard|kdepim-themeeditors|kmail|mbox-importer|pim-data-exporter"
akonadiconsole/unstable,now 4:22.12.3-1+b1 amd64 [installed]
akregator/unstable,now 4:22.12.3-1+b1 amd64 [installed,automatic]
kde-standard/unstable,now 5:147 amd64 [installed]
kdepim-themeeditors/unstable,now 4:22.12.3-1+b1 amd64 [installed,automatic]
kmail/unstable,now 4:22.12.3-1+b1 amd64 [installed,automatic]
kmailtransport-akonadi/unstable,now 22.12.3-1+b2 amd64 [installed,automatic]
mbox-importer/unstable,now 4:22.12.3-1+b1 amd64 [installed,automatic]
pim-data-exporter/unstable,now 4:22.12.3-1+b1 amd64 [installed,automatic]
I don't remember having warnings about them since last weekend. Have you tried different sources?