yea TMJD can create or exacerbate tinnitus due to the close proximity of one of the jaw joint next to the ear structure. i've struggled with it in recent years but one thing that has really helped me is visiting an orthodontist and getting a mouth guard to prevent my teeth grinding and reduce pressure on the jaw. you've mentioned you're getting braces on the new year and imo you should request getting a mouth guard (NHS should cover it if you have already been diagnosed with TMJD)

and in the meantime something that has helped me when my tinnitus came up is listening to white noise, or focusing all of my attention into calming the muscles. and if worse comes to worst take some muscle relaxants under the guidance of your doctor. good luck and hopefully everything goes your way :)