opensuse-security@opensuse.org is subscribed to security-announce@lists.opensuse.org, but delivery is disabled, so those probes should not have been caused by bounces. However:
Aug 10 13:19:17 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 5.
Aug 10 13:19:18 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score 5 >= threshold 5, sending probe.
Aug 10 16:18:54 2022 (1721) Member opensuse-security@opensuse.org already scored a bounce on list security-announce.lists.opensuse.org today.
Aug 10 16:21:00 2022 (1721) Member opensuse-security@opensuse.org already scored a bounce on list security-announce.lists.opensuse.org today.
Aug 10 16:27:10 2022 (1721) Member opensuse-security@opensuse.org already scored a bounce on list security-announce.lists.opensuse.org today.
Aug 10 16:27:15 2022 (1721) Member opensuse-security@opensuse.org already scored a bounce on list security-announce.lists.opensuse.org today.
It is a regular thing:
bounce.log-20220802.xz:Aug 01 15:25:19 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 2.
bounce.log-20220803.xz:Aug 02 13:18:52 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 3.
bounce.log-20220804.xz:Aug 03 10:24:38 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 4.
bounce.log-20220805.xz:Aug 04 13:19:25 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 5.
bounce.log-20220806.xz:Aug 05 13:18:53 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 1.
bounce.log-20220807.xz:Aug 06 16:17:33 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 2.
bounce.log-20220808.xz:Aug 07 16:17:35 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 3.
bounce.log-20220810.xz:Aug 09 13:18:35 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 4.
bounce.log-20220811.xz:Aug 10 13:19:17 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 5.
bounce.log-20220813.xz:Aug 12 19:19:48 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 1.
bounce.log-20220817.xz:Aug 16 01:17:40 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 2.
bounce.log-20220818.xz:Aug 17 16:18:01 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 3.
bounce.log-20220819.xz:Aug 18 10:19:49 2022 (1721) Member opensuse-security@opensuse.org on list security-announce.lists.opensuse.org, bounce score = 4.