Hey @wiztek 
It’s good to hear you love the app!
Like @arthurdaly mentioned, the new AI FTP Detection from the new system is not comparable with the old AI FTP Detection. It’s not an apples, to apples comparison.
This new AI FTP Detection is recalibrated to the new system, thus your fitness has not changed. So no, you’re not slower or getting slower, hehe. Plus a good indicator that this FTP is pushing you correctly is that you’ve been labeling your interval work as Hard/Very Hard.
Much like buying a new weight scale I think this post from Nate may help understand:
As far as the 1 watt increase, I would encourage you to play around with your training plan as @JoeX mentioned, and see how these changes may affect your prediction! You can change your Training Approach, move days around, add or reduce the amount of days you train, etc… The AI Simulation Window is meant to be played with and see live feedback on how your training affects your fitness.
Lastly, I also wanted to say that there are other fitness indicators other than FTP that show you are getting stronger (and not slower) like: recovering faster, feeling stronger, labeling prescribed interval workouts as Hard/Very Hard.