In a medium saucepan, combine apple cider vinegar, granulated sugar, brown sugar, garlic powder, ground ginger, turmeric (if using), salt, and optional crushed red pepper flakes. Stir together over medium heat until sugars dissolve and mixture starts to boil.

Once boiling, stir occasionally for 3-5 minutes to prevent sticking. Look for syrup to thicken slightly.

Carefully add drained canned pineapple chunks to boiling syrup. Lower heat and simmer for 15-20 minutes, stirring gently until pineapple is glossy and translucent.

Spoon the hot mixture into sterilized jars, filling just below the rim. Let cool at room temperature then refrigerate for at least 24 hours before enjoying.