When trying to set a expiration date for share links, the date picker is not accessible, since it is hidden behind the sidebar.
@nextcloud/designers
GitMate.io thinks possibly related issues are https://github.com/nextcloud/server/issues/313 (Path '' is not accessible or present !!!), https://github.com/nextcloud/server/issues/2936 (!!! Path '' is not accessible or present !!!), https://github.com/nextcloud/server/issues/1909 (The dates before 1970 are not well displayed), https://github.com/nextcloud/server/issues/4967 (Dates in the UI don't match), and https://github.com/nextcloud/server/issues/10258 (files dates ( enhancement )).
Hum, I'm almost sure I fixed it on the add note to share.
https://github.com/nextcloud/server/commit/3a11c26cb49c7d5de3410075d86e165a8452a761#diff-786abfdec65b6ba7b37e0daff7bc3b5eR533
Apparently yes
I can confirm the behaviour @juliushaertl describes
@skjnldsv Probably it got changed somewhere else then? The app sidebar has a z-index of 1500, so the 500 from the datepicker won't work:

@juliushaertl fixed in https://github.com/nextcloud/server/pull/10515
Most helpful comment
@juliushaertl fixed in https://github.com/nextcloud/server/pull/10515