I think you’ve answered your own question, in that you’re at the end of a block of training and you’re getting ill. It’s not surprising that you’re feeling fatigued!
I have been focussing on losing weight for the last few months, before starting on my TR plan for the year and during SSB I MV. I have lost quite a lot of weight and with it have also lost a bit of raw power, but my W/kg has increased. That has been with the specific goal of weight loss though, I wouldn’t expect to see a power drop due to weight loss for you training with the calorie intake you describe.
Make sure you’re rested and recovered before starting the next block and taking the ramp test, and then you’ll see where you’re really at. Only worry about it if you do indeed see a significant drop in FTP or W/kg.