There was a post about it on lemmy.ml, it seems there's a delay in synchronizing content mostly due to lemmy.ml being overloaded, sometimes accessing that server gives a bad gateway error.
It does sync anyway, it just requires a bit more time than other instances.
Very much out of sync yes ...
The very oldest post when searching - - for all community at all instances - - from Lemmy.World is 20 days old
...it would be about 4 years old if sync was complete š !