(Very likely #regression from 01936fa)
~~MediaWiki thinks a block duration of "2 days" is an absolute timestamp, thus using an expiry since Unix epoch.~~
MediaWiki formats block duration of "2 days" as a duration since Unix epoch (4 decades, 7 years)
Reported on [[https://commons.wikimedia.org/w/index.php?title=Commons:Administrators%27_noticeboard&oldid=231144612#Inconsistent_lengths_of_block_period|Commons AN]]. I also did a blocking [[https://commons.wikimedia.org/w/index.php?title=Special:Log&page=User%3AZhuyifei1999_%28test%29&type=block|test]] to my test account, and "day" was not the only affected unit.
This bug affects the block log entry display only, not the actual block itself or the database record of the log entry.