“…These findings support the nonlinear relationship between EF and RE through IQI and PDN threshold effects. While prior studies conducted by Naimoglu [ 135 ], Mohammad et al [ 136 ], Sinha and Shahbaz [ 137 ], Sugiawan and Managi [ 138 ], Destek and Sinha [ 20 ], Danish and Ulucak [ 139 ], Alola et al [ 140 ], Qiao et al [ 141 ], Adamas and Nsiah [ 142 ], Diallo [ 143 ], and Sharma et al [ 17 ] have primarily on direct and unconditional effects, they have also supported similar effects of RE on environmental degradation. Furthermore, other variables retain similar signs of the coefficients with highly identical effects on EF in models 3 and 4.…”