Form Recognizer - Changed confidence

Question

I have been running form recognizer with one model for the past 5-6 months. Results for good images were in range 0.9 - 1. I was able to detect anomalies usually if the confidence is below 0.7 range. This weekend form recognizer started returning values in the 0 - 0.3 range for the same model. Something must have changed with the service and I am asking for a Microsoft friend if they know what changed within the black box. I was able to create another model by adding even more images to training set and now it is producing 0.5-0.7 range confidence for a certain fields but far below what I was used to.

Thank you