Good news regarding expiring certificates: 2.23.2.0 is available for download on https://bubu1.eu/cctg and supports re-issueance of such certificates.
After installing the update, it may take up to a day before the reissuance option becomes available.
To learn more about the renewal process, please refer to https://www.coronawarn.app/en/blog/2022-06-01-cwa-2-23/.
f-droid.org builds are unfortunately not going to be available until the latest reproducible builds issue is resolved (https://codeberg.org/corona-contact-tracing-germany/cwa-android/issues/265), sorry.