Petr Bodnár thanks for your feedback I reopened it but lowering to critical as we lived with the issue for a year I don't think this should block releases.
Can you specify which language you use for your wiki? Also do you know if the email templates for notifications have been customized on your side? And is this a fresh install of 15.10.8 or an upgrade from an older version? Thanks!

(BTW when speaking about e-mail notifications, I don't get any since 2021 from this Jira, I have no idea why - can you please check on your side? I need to come back to my watched issues once in a while to see what's new now...)

About that we also have the issue, I'll try to see again with our infra if we can fix this it's annoying for everybody.