Why Southgate brought on Grealish, then substituted him 35 minutes later?

Gareth Southgate decided to substitute his sub Jack Grealish after the second goal. Was it a tactical decision? Or it was something that he is going to criticize about. The game was controversial where they say sterling dived and England Vs Denmark was unfair. But under the limelight was Jack Grealish. What do you think of Southgate's decision?

Видео Why Southgate brought on Grealish, then substituted him 35 minutes later? канала Goal 90