BibTeX does not have the right entry for preprints. This is a hack for producing the correct reference:
@Booklet{EasyChair:9177,
author = {Yulia Normanskaya and Denis Dogadushkin},
title = {Relics of the Finnovolgian Accent in the Seto Language},
howpublished = {EasyChair Preprint no. 9177},
year = {EasyChair, 2023}}