Dementia

“Another fear of mine is early onset dementia.”[1]
A strong explanation for DeepLeffen’s contradictory information in his accounts is that he has dementia or memory loss, and is therefore an unreliable narrator.
The following are possible symptoms of dementia[2] along with some direct examples from DeepLeffen Lore.
* Recent memory loss: 
** “Can’t remember any of my memories, lol. Pretty sure I'm fucking sick tho.” [3]
** “Last day for the DBFZ subgoal with mango, LOL. I have no idea who the fuck he is or why I think so much about him.” [4]
** “I can barely remember my kid’s name, lol." [5]
* Problems communicating:
** “You can also find me on Twitter. You can also find me on Twitter. You can find me on Twitter. You can find me on fucking Twitter. If you or your friends can find me on Twitter, Find me on Twitter. Find me on Twitter if you or your friends can, you won't.” [6]
** “I only had one problem; I knew the names of every Kirby, but I had no idea how to pronounce them.” [7]
* Disorientation/ Difficulty completing familiar tasks:
** “I've been working my ass off several hours a day (9 months in Leff years) trying to figure out how old I am.” [8]
* Problems with abstract thinking:
** “Jennie tried to learn how to train them and I said, “don’t bother, it takes you 1 1/12 hours to learn the same thing it only takes me 5 hours to learn.” [9]
* Misplacing things:
** “If you want some really cool tips and combos, there is a good ass video for learning them all but I can’t remember where it is or how I found it or what it is or where I found it. Let me know if you know what I’m talking about.” [10]
* Mood changes/ Personality changes:
** “Easiest way to deal with toxic people is to get well acquainted with them personally. If you are kind to them, they will be kind to you. Toxic people cannot survive in positive and healthy environments. I like to pretend I'm someone else and send them death threats.” [11]
** “At the end of the day, the responsibility is on every one of us to build the community we want see in the world.  We have a choice to be kind and loving to everybody we meet, or to join the chorus of voices promoting hate and toxicity. Our biggest weakness is that we refuse to take ownership of our community. We are only as good as our worst representative. Do we want the community to be a place where we can feel safe together?  Or do we want to find reasons to hate one another and grow distant? If we can't decide as a community the path we want to take, let me know. I will happily hurl the first insult. I will happily ridicule people for their playstyle. I will set fire to a Nintendo executive’s house with their family inside. Just let me know." [12] [13] [14]
* Loss of initiative: 
** None yet… seemingly.
Direct evidence such as this leaves little room for other interpretation. It is easy to interpret his lack of coherent thoughts as a different universe with different mechanics entirely. However, connecting direct examples to eight of the nine symptoms of a real life mental disease, combined with his seemingly lack of incoherence, makes this a strong candidate mechanic in the DeepLeffen Alternative Universe.