Deubiquitinating enzyme exhibiting a preference towards 'Lys-63'-linked ubiquitin chains. Thiol-dependent hydrolysis of ester, thioester, amide, peptide and isopeptide bonds formed by the C-terminal Gly of ubiquitin (a 76-residue protein attached to proteins as an intracellular targeting signal). Belongs to the peptidase C19 family.