In the user block log, the block duration is displayed as a UTC timestamp. All other timestamps are in the local or user timezone. This behavior highly confusing if you don't know about it, and often leads to wrong block durations when a block is reinstated.

Example: User:195.191.253.151 on dewiki, block as of 2016-03-30T12:27:07 CEST:

• I entered 2016-03-31 12:30 on [[Special:Block]]. This timestamp was interpreted as CEST (= 2016-03-31 10:30 UTC).
• In the block log, the timestamp of the block is shown in the local or user timezone (CEST for me). But the end of the block is shown in UTC.
• The user can't tell that the two timestamps are in different timezones.

There are at least two possible solutions for this problem:

• Display block durations in the local or user timezone.
• Add the timezone to timestamps that are not shown in the local or user timezone.