Johnson was Spurs’ top scorer in 2024-25, with 18 goals, including the winning goal when the London club beat Manchester United in the Europa League final.
But he has found himself struggling for playing time under Frank, who replaced the sacked Ange Postecoglou in June.
Johnson makes his fifth Premier League start of the season when Spurs host Manchester United on Saturday having pressed his case with a goal in Tuesday’s 4-0 Champions League win over Copenhagen.
But Johnson then became a potential subject of questions upon being sent off, as he became the first British player to score and see red in Europe’s premier club tournament.
“It’s been a change for him with the arrival of a new coach,” said Bellamy, who is preparing for November’s World Cup qualifiers against Liechtenstein and North Macedonia.
“Last season was not a great season for Spurs, but he stood out in certain parts and his numbers and goals were exceptional.
“I’ve been there myself and it’s difficult when someone new comes in and you see one or two more players. So I feel like he’s adjusting to that and the new coach is adjusting to him as well.
“I always believe quality will shine through and I am sure that will be the case for Brennan.”
Wales will visit Liechtenstein on November 15 and host North Macedonia three days later.
Wales are three points behind North Macedonia, second in Group J, although Bellamy’s team has a game in hand.
After earning a place in the World Cup qualifying Nations League in March, Wales would have a play-off semi-final at home if they manage to secure second place in the group.