Just guessing here, I googled up "yuku" special class (as 行くappears to be according to jisho.org and your question concerns the ending "yuku") and I came up with this: https://japanese.livejournal.com/932203.html.
Beyond the て form conjugating って despite being a verb ending in -, I can't find any other significant differences compared to other verbs. Just to make sure, did you check whether it makes sense that his ゆく might be some slang form for 〜ておく or alike as stated in the link I provided for とく?
よく分からない!
kind regards.
It expresses the process of changing from one state to another or to go on while remaining in some state.
https://jisho.org/search/*%E3%81%88%E3%82%86%E3%81%8F
https://jisho.org/search/*%E3%81%AB%E3%82%86%E3%81%8F
https://jisho.org/search/*%E3%82%8C%E3%82%86%E3%81%8F
https://jisho.org/search/*%E3%81%A1%E3%82%86%E3%81%8F
I see, thank you!!
”ゆく” attached to verb stems?
I have heard of 行く(ゆく) sometimes being attached to a verb in the て-form, but can it also attach to verb stems? Does it mean something different? I found 薄れ行く in a search, but it treated it as its own verb (with the same exact meaning as うすれる anyway). Can someone help me understand this?