I blocked an user account for 18 month on 24th december 10:55 local time (UTC+1). The api block entry looks ok except one hour difference which might be the leap time [1]. The api event log is also ok [2]. But the special page expiration time [3]

with an expiration time of 1 year, 181 days, 17 hours, 10 minutes and 48 seconds

looks very strange.

[1] https://de.wikipedia.org/w/api.php?action=query&list=blocks&bkusers=Meister_und_Margarita
[2] https://de.wikipedia.org/w/api.php?action=query&list=logevents&leuser=Xqt&leaction=block/block&letitle=Benutzer:Meister_und_Margarita
[3] https://de.wikipedia.org/w/index.php?title=Spezial%3ALogbuch&type=&user=Xqt&page=user%3AMeister+und+Margarita&year=&month=-1&tagfilter=&hide_thanks_log=1&hide_patrol_log=1&hide_tag_log=1&hide_review_log=1