What internal evidence do you have to say that 1 Enoch is pseudepigrapha?

For Christians who believe 1 Enoch is pseudepigrapha what internal evidence do you have? A professor saying "trust me bro I'm a professor" is not evidence. In other words, for Christians who believe that 1 Enoch was first written 300 BC, and then deliberately deceptively backdated to make it look like it was written by Enoch 7th generation from Adam before Noah's flood -- as that is what internal authorship claims -- what evidence do you have of this? In case someone does not know what pseudepigrapha means, here's the [origin and history of *pseudepigrapha*](https://www.etymonline.com/word/pseudepigrapha) from the *etymonline* website: > **pseudepigrapha**(n.)
"books or writings of false authorship," 1620s (implied in *pseudepigraphical*), especially of spurious writing professing to be Biblical in character and inspired in authorship, from Modern Latin use of Greek neuter plural of *pseudepigraphos* "with false title," from *pseudos* "a lie" (see [pseudo-](https://www.etymonline.com/word/pseudo-)) + *epigraphē "a writing" (see [epigraph](https://www.etymonline.com/word/epigraph)) . **Note**: I mean what internal evidence in 1 Enoch do you have that it was first written 300 BC, and not pre-flood by Enoch 7th from Adam? I know a lot of people like to refer to authority figures, and majority to get their opinions, but for this question I am asking for *internal evidence*. Actually you can use evidence from archaeological writings/inscriptions from the Ancient Near East to argue against it if you want, e.g. the Dead Sea Scrolls.