This image might make the issue clearer: https://i.imgur.com/6PFLDeWh.png

What happened is that what used to be called DST is now considered the standard time for this timezone, and what used to be standard time is now *negative* DST.

Here are the last transitions in Africa/Casablanca output (rearguard

format):

transition,type,[UTC time],[Type offset],[Type isDST]
3672612000,1,2086-05-19T02:00:00Z,PT1H,DST
3699828000,2,2087-03-30T02:00:00Z,PT0S,STD
3703456800,3,2087-05-11T02:00:00Z,PT1H,STD

So change is from standard to standard, even though offset changes from 0h
to 1h. Is that expected behaviour?