Catalysis of the reactions : D-galactosyl-3-(N-acetyl-beta-D-galactosaminyl)-L-serine + H2O = D-galactosyl-3-N-acetyl-beta-D-galactosamine + L-serine and D-galactosyl-3-(N-acetyl-beta-D-galactosaminyl)-L-threonyl + H2O = D-galactosyl-3-N-acetyl-beta-D-galactosamine + L-threonyl.
D-galactosyl-N-acetyl-alpha-D-galactosamine D-galactosyl-N-acetyl-galactosaminohydrolase activity