Searching for the coordinates at Gaia i found it with the name Gaia20bky.
And i agree with you, Taichi Kato, the light curve is quite similar to a SN.
There is few data, but the shape is evident.
From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>
Sent: Friday, June 2, 2023 1:51 AM
To: vsnet-chat@ooruri.kusastro.kyoto-u.ac.jp <vsnet-chat@ooruri.kusastro.kyoto-u.ac.jp>; vsnet-newvar@ooruri.kusastro.kyoto-u.ac.jp <vsnet-newvar@ooruri.kusastro.kyoto-u.ac.jp>
Subject: [vsnet-chat 9418] ASASSN-20dj: SN
ASASSN-20dj: SN
The ATLAS light curve looks like to me an SN (relatively
slow rise to maximum and faded in several months).