BibTeX does not have the right entry for preprints. This is a hack for producing the correct reference:
@booklet{EasyChair:4814,
author = {Alexej Pynko},
title = {Three-Valued Logics with Subclassical Negation},
howpublished = {EasyChair Preprint 4814},
year = {EasyChair, 2020}}