Can't remember who, but someone on this thread earlier brought up the issue of pitch doctoring to favor certain types of bowlers.
The difference between the ball-change situation last night and pitch doctoring, or pitches that offer an excessive amount of assistance for bowlers (e.g. Gabba 2022, Indore 2023):
Yes, although those pitches produce an uneven balance between bat and ball, it doesn't constitue unfair play between the two teams in the sense that both teams had to bat and bowl on the same pitch (the exception being if the pitch was tampered with in the 4th innings, meaning the bowling team wouldn't have to bat on the tampered surface).
Using the pitch analogy, the situation that happened yesterday with the ball change would be the equivalent of changing pitches during an innings. One moment, you're playing the match on a flat track that is a batsman's paradise. Then the umpire says at the lunch/dinner break to the batting side "ok guys, after the break, we're going to resume the game on another pitch that is 10 metres away", and the second pitch after the break offered an excessive amount of turn, bounce, seam/swing movement right from ball one. Unfair play and an unfair contest.
What happened yesterday definitely constituted unfair play. NO, it was not cheating from England as they didn't choose the replacement ball. However, there's absolutely no way they would've bowled Australia out with the ball that was used in the first 38 overs. Furthermore, McCullum and the Poms would've been bitching deluxe if the roles were reversed, and it was Starc/Cummins/Hazlewood achieving that excessive amount of swing and seam movement from a replacement ball that Woakes and Broad got yesterday. Not only did the replacement ball look much less than 38 overs old, it also had a more pronounced seam (especially on the second split-screen shot that Sky Sports took of the difference between the two balls), hence offering massive assistance to the bowlers.