is d2 clone walk backward? like s5 to s4 instead of s6

This is an old bug.

Each realm consists of many servers (hundreds). Sometimes some of the servers in a realm start misreporting the dclone status on one game mode, while some servers report the correct status. When you create a new game your game is hosted on a random server (well, it may as well be random for all intents and purposes, there's no way to control it). If the game you created is hosted by one of the servers with incorrect status reporting, you will see the wrong status. If your game is hosted by one of the servers with correct status reporting, you will see the correct status. There is, however, always only one actually correct status. From a user standpoint, just by being in a game and using /uberdiablo, it's impossible to know which is correct and which is not. Bottomline is, the servers never go back in status, it's just some servers reporting the wrong status.

When this happens, an automated tracker may also get confused, because it has no way of knowing if it is connected to a server reporting the correct status or to a server reporting incorrect status.

This happens more often on ladder than on non-ladder because there is more dclone activity on ladder.

The problem usually resolves itself (= all servers reporting correct status again) after dclone actually walks next time, but if that takes a while, it can go on for a long time with conflicting status reports. The longest such instance on softcore ladder that I can recall was a few years ago was when it was incorrect on one region for 1-2 weeks. Then there was a walk and it was all good again.

Here are two old (2+ years) threads about the same problem:
forums/scamming-with-dclone-reports-t1415375.html
forums/false-dclone-alart-t1425898.html