This concern was already explained previously regarding latency/lag effects during fast time controls such as bullet chess - 

https://www.flyordie.com/forum/255679

What you are seeing is not the game “rigging” clocks or making time move backwards.  During connection instability or delayed synchronisation, the opponent’s moves may appear to arrive suddenly once the server catches up with the transmitted data.  In bullet games especially, even very small delays become much more noticeable.

A player making several moves quickly after a temporary stall does not mean their clock stopped on the server side.  It usually means your client received the queued moves late due to latency between device, network, and server.

As this is the same issue already discussed before, the explanation remains unchanged.  If the problem continues frequently, testing with a more stable connection (preferably wired instead of Wi-Fi) is recommended.

Please avoid repeatedly opening new topics about the same issue.