Considering nobody has strength when they start to fish, and strength was added to many fish types, could that also play into it? You said that minnows and sunfish have 0 strength, but what about Eels and catfish, ridgebacks, snails ,etc?
If STR only affects how frequently it jerks, something else is affecting reel speed because the reeling is definitely slower, STR being a factor or not.
Like I said, some fishermen were using STR potions to reel in fish faster.
Another thing regarding the red line cooling down slower is that I used to be able to keep my hand on the reel and hold it there while the line cools off. Now, I notice that the micro movements from holding the reel actively will interfere with the cooldown on the line, making it so that I have to fully release. While this is a minor point, it also adds up to just things making fishing harder. It’s like the mechanics checks to see if there is any movement at all on the reel before counting down to allow the line to cool off.