In recent years, ZNS has attracted mobile manufacturers with its fascinating features and is expected to be merged into the mobile I/O subsystem. In the meantime, F2FS is one of the feasible options to support ZNS in mobile devices since F2FS adopts append-only write policy. However, F2FS significantly suffers from filesystem-level garbage collection (GC) and it increases the tail latency of foreground applications. To overcome this problem, we propose a new F2FS GC scheme, which preempts the ongoing GC when it is beneficial, in order to prevent the foreground applications from waiting for a long time. Our evaluation demonstrates that our scheme reduces the tail latency of foreground applications by up to 87%, compared with the conventional F2FS GC scheme.