The winger has been in good form over the past few games, scoring in several contests.
He netted the first in a 3-0 thumping of Manchester United at Old Trafford on Sunday.
Maddison was asked about Johnson having posted an image of himself mocked up as Ronaldo.
This week, Maddison stated at his UEFA presser, “Brennan is first and foremost he’s a very good friend, I’m close with him. I think a lot has made of him coming off social media which to him was probably not such a big thing.
“He’s the type of guy to have a break from that stuff anyway. People have maybe read too much into it too much but since then gone four in four I don’t think I’ll be telling him to redownload anytime soon… He’s a great kid, a brilliant player.
“No-one has every doubted that but he’s really showing it at the minute consistently. It’s not easy to score four games in a row. He’s a brilliant lad and a great friend of mine so I’m always there for him.
“That picture was a bit tongue in cheek, we found it funny when it was put in our group chat. But hopefully he can continue this form because he’s a real threat for us. He can do damage to a lot of oppositions in the Premier League and Europe so I like to see him in that rich vein of form.”