The last part is true. Speaking from experience, cortisone shots can create tendon issues. I’ve torn two tendons and after evaluating the MRI, the ortho said the fraying of tendon fibers that eventually snapped was largely due to overaggressive conservative treatment of tendinitis- which means administering cortisone shots way more frequently than typical, mainly to avoid surgery, while allowing me to continue competing and to also provide relief. I trust this guys opinion as he was part of the medical team for the Dodgers, Lakers, Ducks, and Kings and has seen tons of similar issues with athletes.