“…However, this is the beginning of dealing with η-Ricci solitons and spacetime physics. In the future, we will focus on studying various types of solitons in Lorentzian manifolds combined with singularity theory and submanifolds theory, presented in [11,12,20,25,[32][33][34][35] to obtain new results and theorems. Many problems of spacetime symmetries and Ricci soliton are still unresolved, and we hope that the readers of the present paper can do a good amount of work on the subject.…”