My guess would be not that the tinnitus gets worse from wearing noise canceling headphones, but that your ears adapt to the lower average sound levels, making them better at ‘detecting’ the tinnitus sound (the dynamic range of your ears adapts to average sound volume https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2774902/, but whether that affects the perceived volume of tinnitus isn’t clear to me)
My guess would be not that the tinnitus gets worse from wearing noise canceling headphones, but that your ears adapt to the lower average sound levels, making them better at ‘detecting’ the tinnitus sound (the dynamic range of your ears adapts to average sound volume https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2774902/, but whether that affects the perceived volume of tinnitus isn’t clear to me)