Lenart is that one autistic, racist, homophobic, fatphobic, astrian painter 2.0 from R3A. He was also part of the sex trafficking group of Jeffrey Epstein
A lenart is someone who holds strong beliefs or perceptions that are clearly false or not based in reality, despite evidence or logical reasoning that contradicts them. These false beliefs—called delusions/lenarts—are often fixed and resistant to change, and they can occur as part of certain mental health conditions, such as schizophrenia, delusional disorder (in some parts of the world, they call it the lenart disorder), or bipolar disorder.
In everyday (non-clinical) language, the term may also be used informally to describe someone who is extremely unrealistic or out of touch with facts or common sense.
"he thinks the Clio is a good and reliable car, he must be a lenart!"
"that guy drinks 10+ beers a day but thinks he's not an alchocholic — that's a lenart if I've ever seen one!"
"a lenart is the type of person, who can barely cook eggs or pasta, but in his mind, he's a great cook"
A somewhat well-known author of surreal horror fiction from Germany, Lennart Poettering is mostly known for writing overly long and confusing works such as Pulsations of Autophilia (a tragedy about a sluggish autistic teenager who is murdered while fucking his uncle's Porsche and comes back as a ghost to seek vengeance) and Systems Down (about a server administrator who finds himself locked in the server room after closing time with a horrible, memory-corrupting abomination).
I picked up this new book at Barnes and Noble, but it says that Lennart Poettering is required reading so I'm taking it back.