in survival/creative I kill chickens with iron sword and bow (enchants, looting, unbreaking, punch, power) and chickens ALWAYS drop cooked chicken
I have no flame enchantments.
I can provide video evidence
Environment
java 64 bit version 191
os windows 10
16 gb memory
gtx 1080 ti
I7 7700 4.2ghz
JAVA Minecraft 19w03b
Outdated data pack