FlytrapCare Carnivorous Plant Forums

Hello everyone! Sorry if this is a dumb question, I recently started getting back into growing venus flytraps and I am still new to the ins and outs. I tried doing all the research I could by browsing YouTube, Reddit, and a couple forums. I cannot figure out what is wrong with my flytrap. It looks like something is chomping away at the leaves, but I cannot figure out what exactly is wrong. Is it a bug, does it have a disease, or am I doing something wrong?

I've been using only rain water to water the plant, and recently changed the medium from what it came with to a premix from Amazon. When a new trap grows, it'll grow normally and then start withering away like that. It looks like something is eating it, but the plant stays indoors and I don't see any bugs or mites on it.
I originally bought the plant from Safeway, in those little clear plastic tubes. I kept it in the original pot for a while until it started to die prematurely and get leaf damage, then I changed to a bigger pot with new dirt. I also got a grow light and gave it 8+hrs of light on a timer when I started getting deformed traps and them dying before getting to full size. Now I am getting much bigger baby traps, but I cannot solve this leaf damage.

It doesn't really appear to be nibbled on, but it looks to be slowly dying due to lack of light, and may be trying to enter dormancy.
VFT's need at least ~ 6 hours of direct, unfiltered sunlight, or strong artificial light to the tune of 12+ hours a day, usually more. Chances are, the light you're using is insufficient. Plus, it's the time of year for them to sleep, but it can't because you're forcing it to stay awake.
Put it somewhere that is dark and cool (a garage that stays above freezing is perfect), and let it sleep until the temps stay above freezing at night in the spring. Then, when winter is over, put it outside where it gets direct sunlight.