Inter nodal space too short

Hello there. Generally I prefer short internodal spacing and some growers agree some don’t. Raising lights would increase internodal spacing. The reason I prefer it is because it leads to more compact cola development which can be desirable based on space limitations or grow method like SoG. I would not correlate short internodal distance with slow growth. Generally short internodal distance means you have light to canopy distanced correctly dialed. But that would also mean you have the right lighting conditions for optimal growth (with VPD correct) and you are stating its slow going. That would lead me to look at other reasons why the plant is not growing - it’s not your lights. Stem looks fine its not thin for that size plant. You can look into things like silica if you want to provide your plants some nutrition that helps strengthen plant and increase resistance to stress/pathogens/etc. i use Diatamaceous earth as a top dressing for IPM then water it in for a silica boost up to week 3 of flower. Hope this helps get the gears turning, we are here to assist even more so keep asking questions. Good luck