I’ve made kimchi before, but under the supervision of my mom. So I’m not exactly an expert.
To me it looks like your kimchi is too watery. After looking at the recipe I think I may know why. This is a vegan recipe, traditional kimchi not only has fish sauce, but it also has quite a bit of fermented shrimp brine.
It doesn’t look like the recipe you linked has enough salt in the actual spice mix, traditional kimchi gets this from the shrimp. If you don’t have enough salt, the marinade won’t fully saturate the cabbage.
If you are trying to do a traditional vegan recipe I would suggest just doing This but substituting salt for the shrimp, and something like tamari or something with umami for the fish sauce.
I actually don’t know if I would use that recipe, it seems low on both sugar and salt for preservation.