QED and accretion flow models effect on optical appearance of Euler–Heisenberg black holes Xiao-Xiong Zeng, Ke-Jian He, Guo-Ping Li, En-Wei Liang and Sen Guo Eur. Phys. J. C, 82 8 (2022) 764 Published online: 30 August 2022 DOI: 10.1140/epjc/s10052-022-10733-y