Fuel smell in cabin

[Danishp97]

Hi, my car has VRSF catless downpipes and tune.
Got my oil changed and put in new bmc airfilter
Car was driving fine, 30 mins into the drive did a pull and then when I slowed down the cabin was smelling of fuel. No smoke from exhaust nothing, no underbody leaks. Drove a little after that the smell went down but as soon as I would stop at a red light the cabin would smell again.
Didn't risk it and sent the car back on a truck.

Any clue what could it be? Could the maf sensor be messed up while installing new air filter?

Any suggestions would help.