Depends on how you define ‘cheating’.
If your definition of ‘cheating’ in the context of GoW AI is that factors influencing outcomes are not the same for all players at all times, then we do know the AI cheats.
The devs have admitted to as much:
So we do know the game is designed to favour newer players.
How do we know the game isn’t designed to disadvantage the player every n-th PvP battle?
Or designed to increase skulldrops until a level >1350 player loses their n-th PF500 run?
The problem with terms like ‘bug’ and ‘cheat’ is that the game doesn’t have bugs or cheats according to the devs because things are designed to be that way.
‘It’s clever design, not cheating!’ - even if everyone else disagrees. Remember, semantics are more important to the GoW team than making the game better! 
Why? That’s a lot of work for (likely) little to no benefit as people have learned the hard way. Even if numbers were to prove anything, what are the chances of anything changing for the better for players or them starting to show accountability?