RPM and Power goes down while I have to push much harder

I’ve searched the forum but couldn’t find a solution or topic which gave me a reason/solution for the problems I’ve encountered several times.
While doing a workout it happens several times that all of sudden Zwift says that my RPM is decreasing and the Watts I’m pushing or decreasing to.
But in reality my smart trainer is giving me a lot more resistance, sometimes even so hard that my I can smell the rubber of the tire. So I really have to push harder and harder while Zwift tells me that the watts I produce are decreasing really fast.

Most of the times it’s happening after half an hour of training or when I have to change my RPM in my workout.
I’ve already changed my tire, connected my laptop with a cable instead of using a wireless connection, calibrated my smart trainer several times.
Anyone who can help?

Are you familiar with ERG mode where the workout controls you’re power by increasing resistance automaticallly

Yes I am. I use ERG for workouts. But when I have to change my RPM or power I always encounter those problems.

When I changed from a wheel on turbo trainer to a direct drive turbo I found that instant increases of power in ERG were impossible to achieve.
Because the resistance was applied too quickly my cadence would drop, meaning the resistance would increase even more and got into a vicious circle.
I’ve learnt to ensure I pick cadence up significantly just before the next workout stage.

Is it just on big power jumps or more general?

It’s not only when I have power jumps. this morning f.e. I had to raise the RPM from 85 tot 90RPM and increase power by 40 watts and after some seconds I had to push really hard, but Zwift said I was pushing only 100 watts at 30 RPM. In real I think I was pushing more than 500 watts at 90-100 RPM.

Just picked up on the tyre smell. Double check your tyre pressure and if the roller is close enough to the tyre. Could just be slipping as everything warms up and not transferring all your power to the turbo.

Is your cadence coming from the turbo as well? If so would make sense.

If cadence is coming from a sepearte source then won’t be what I said above obviously