stunted or just genetics

Based on growth nodes, looks like it may have been stunted early on, but seems to be recovered lately... extrapolating from internode length. the bottom 2-3 oldest nodes are super tight, then you have fairly normal distance between the top few nodes. bacareful using something that reflects light like a mirror. white paint is better than aluminum foil and even some mylar for that matter. i see that may not be what i thought but if it can crump and re-open to a flat surface, that'll reduce any potential hotspots... kinda likea diamond stamp on mylar. anyway, flat white, polyfime (aka panda film) and some sort of stamped mylar are good options for reflecting light. I doubt this was the cause. More likely light was too close for stage of plant early on. based on recent growth pattern, i'd keep doing things the way you have been doing things lately in that regard -- distance from lamp, hours per day, whatever, it's all relative. leaves look healthy and happy. observe resulting internode length over time and allow that to dictate any increase or decrease to light intensity (distance, dimmer, but distance is better option in most contexts of small adjustments)