After a server reset, inactive players are removed from the ladder. In casual ladder, it removes all players who haven't played in the last 30 days, while in 1v1 ladder, it removes all players who haven't played in the past 3 days. This makes 1v1 ladder extremely sparse after server resets.
Per mankarse:
The WHR code is a bit hard to understand, but as far as I can tell, the difference is in Player.UpdateLadderRatings(): https://github.com/ZeroK-RTS/Zero-K-Infrastructure/blob/d038d39ac03c15bce40758391ec97e80790b22d6/ZkData/Ef/WHR/Player.cs#L253C22-L253C43
MatchMaking uses GlobalConst.LadderAverageDays (3)
Non-MatchMaking uses GlobalConst.LadderActivityDays (30)
GoogleFrog could answer whether this is intended behaviour, or an unintended consequence of a change made for a different purpose
Something I found noteworthy, the time period used seems to be offset to several hours prior to a given server restart, so a player who last played on 1v1 ladder ~80 hours before the server restart probably remains on it while a player whose only game in the past week was 4 hours before the server restart is probably removed from the ladder.
After a server reset, inactive players are removed from the ladder. In casual ladder, it removes all players who haven't played in the last 30 days, while in 1v1 ladder, it removes all players who haven't played in the past 3 days. This makes 1v1 ladder extremely sparse after server resets.
Per mankarse:
Something I found noteworthy, the time period used seems to be offset to several hours prior to a given server restart, so a player who last played on 1v1 ladder ~80 hours before the server restart probably remains on it while a player whose only game in the past week was 4 hours before the server restart is probably removed from the ladder.