England won their Nations League encounter 3-1 in Finland, with Trent Alexander-Arnold and Declan Rice also scoring.
Grealish later said: "We could have had a few more but it was difficult at times.
"The goal came from the manager letting us play with that freedom. I play with Angel Gomes in training and I know what a top player he is. The celebration was for my little daughter.
"I joked to Trent before the free-kick 'score this I will give you 500 quid' and he slapped it in top bin.
"Whatever happens with the England manager, people will always say negative stuff.
"Before people were crying out for all attacking players to play and it didn't work. I don't get it, it can happen in games. I love coming here, a top, top manager and I love playing for him."