Looks like light burn. Regardless if it was close or not.
Second option is leaf deterioration due to end of life
My Mango smile did that as I waited for thrichs to turn ambers, but it was the sugar leaves that turned yellow brown and totally crispy.
I can't yell in the pic if that was at one point sugar leaves of not. If so it could of just been end of life.
If you sprayed any sprays it could of been this, it also could of been a pest. Might want to verify if you have and creepy crawlers, worms or things that fly!
More then likely end of life if it is leaves that curled in, if not it's probably light burn.
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