many unassigned fungal sequences

And I find the taxonomy barplot of Z4 is kind of strange. Z4 has the most sequences after quality control, but most the sequence are only annotated to ‘k__Fungi;p__Fungi_phy_Incertae_sedis;c__Fungi_cls_Incertae_sedis;o__Fungi_ord_Incertae_sedis;f__Fungi_fam_Incertae_sedis;g__Fungi_gen_Incertae_sedis;s__Fungi_sp;__’.

Do I need some other steps to deal with this data?