My Photoshop 2024 Paint tool keeps turning into the Burn tool

Why is my Paint tool malfunctioning in Photoshop 2024?   Was it a settings change made by my mistake or a bug in Photoshop 2024.  Its been going on for 3-4 days now.   I barely ever need the burn tool.    Why does it keep taking over the Paint Tool?    I have a 2020 Macbook Pro, with M2.  I am using the latest update of Photoshop 2024