Janson is the latest high-profile departure from ARG following the likes of CEO Matt Braid, part owner and powerbroker John McMellan, event and category manager Ken Collier, S5000 creator Chris Lambden and media chief Grant Rowley.
Motorsport.com understands that for the remainder of the season the production will effectively be taken in-house at AVE and overseen by Greg Sita, a decision made by ARG owners Garry and Barry Rogers.
AVE has been supplying the hardware for the SpeedSeries production since ARG split with Supercars Media at the start of the year with Janson then heading up the coverage that appears on Stan Sport and the Nine Network.
That coverage includes top talent including Matt White, Molly Taylor, Richard Craill, Matt Naulty, Greg Rust, Chris Stubbs and Fabian Coulthard, with ARG responsible for sourcing that talent.
Janson has effectively headed up the ARG/SpeedSeries broadcast since TCR Australia debuted back in 2019.
ARG declined to comment when approached by Motorsport.com.
Janson's departure casts further doubts over the future of ARG as a number of its categories continue to struggle.
TCR Australia grids slumped to just 13 cars at the recent Queensland Raceway round, although a boost is expected for the upcoming World Tour rounds at Sydney Motorsport Park and Bathurst.
The success of those World Tour rounds could prove pivotal in the future of the domestic TCR series.
S5000, another ARG owned and run category, could feasibly shut down at the end of this season due to poor grid numbers.
There were just nine of the V8-powered open-wheelers on the grid at The Bend last weekend, with rumours swirling since the Sydney Motorsport Park round in July that this will be the last season.
Even if the category does continue, it is thought that Motorsport Australia would review its holding of the prestigious Gold Star, one of the highest prizes in Aussie racing.
Garry Rogers Motorsport is the technical partner for S5000 with the team also running the majority of the cars left in the series.
There was a slight upswing in Touring Car Masters numbers at The Bend, while Trans Am has been a ray of hope with competitive grids, although they too have flat-lined as the season has worn on.
GT World Challenge Australia, which is promoted by ARG, has been solid in recent rounds.
As of this year, ARG and Motorsport Australia have worked as a unified body to run and promote the SpeedSeries events.
However the sweeping changes at ARG could see that change next year, with the current arrangements also likely to come under review.
Among the arrangements is the TV rights which, under the current agreement, are controlled by ARG – something that will almost certainly be reviewed by Motorsport Australia at the end of the season.
What isn't in doubt is the immediate future of the SpeedSeries, with Motorsport Australia thought to be planning the 2024 season.
The governing body already promotes the Trophy Series, a kind of second-tier to the SpeedSeries, as well as the Australian Rally Championship and the Australian Off Road Championship, along with its SpeedSeries involvement.
