Congratulations on your improvement on your 20 min max!
Distinguishing form from fatigue can be determined by subjective and objective measures outlined in the article. Ask yourself these questions:
- Does RPE ( rate of perceived exertion) reflect the training zone (heart rate or power)?
- What is the trend on morning resting heart rate or hrv?
- Are training power targets being consistently attained?
- What is the level of enthusiasm for training?
If you listen to your body’s signals, you’ll be golden. Realize oftentimes less is more. Hope that helps.