u/Ok-Cheesecake-6031

I am pretty new to making vinegar, and I have recently been making batches of red and white wine vinegars. During the first 2-3 weeks when the pellicle is starting to form, the vinegar smells and tastes beautiful, vibrant, and very sour. After around 5-8 weeks, once the pellicle is thick, it starts to develop a weird mushroomy flavor to it and the vibrant notes are dulled. Am I fermenting the batches too long? Is it possible it is fully converted to vinegar in 2-4 weeks? Can the pellicle contribute to the mushroomy flavor? I am using store bought wine, diluting it to ~7.5% abv and letting the sulfites off gas for ~48 hours before inoculation. Has anyone else experienced this? Any advice would be greatly appreciated.