I’m on an Advair inhaler, a “triple spray” nasal spray Mayo mixes that contains Mometazone and sinus washes with Mometazone that is mixed by local lab. Like you, I’ve had problems with thrush. They probably all contribute, but Mometazone sinus rinse seems to be the tipping point for me and I have stopped it a few times due to the thrush.

What has helped me tolerate the steroids better is brushing my teeth after I do the meds and gargling with warm water or salt water a few times afterwards. Before I clean mouth and throat. I even tip my head back about 5” after the nasal rinse to make sure the mometazone is done and doesn’t continue to trickle down. I also use cheap tooth brushes and change them frequently and open a new one once thrush has cleared.

You are probably doing these things, but just in case…
Good luck!