"Proper" conjugations are not totally settled, especially given its slang nature. Yeet does feel like it might be strong (stem-changing), though there's really no authority on it. Interestingly, I found through googling that there is a version of the verb yeet stemming from Middle English verb yeten, which has two variations. The first meant "to address with the pronoun ye" (e.g., as opposed to thou) and had weak conjugations (i.e., yeeted/yeted). The other sense referred to pouring or moving liquids and could be either strong or weak (simple past: yet or yote, or yeted; participle: yote, yoten, yeted). So, looking for historical comparisons is also unhelpful.

Edited for TLDR: no one knows, both forms have historical support; it doesn't matter, go crazy