TPxEdrTzcS4P this has been the issue and based on available info will remain so since day 1 of Apex. Engine seems to be handling audio poorly.
Situation where you don't hear enemy coming from behind has been present as long as I can remember.
Also Horizon (I assume due to passive skill) has been even more stealth than other legends.
Also annoying setting that over time was tuned down yet is still annoyingly high - teammate footsteps, especially tank legends and Loba with her sexy high heels :)
As for hitting sound - yeah, that has been my complaint since I started playing in season 7. Especially with high damage 1 shot weapons like snipers and marksmen it is essential to know when you get hit, but in many cases you just "feel / hear" 1 hit but are knocked and only in death summery see that the person has headshoted or what not you before, sometimes multiple times. Feedback of a hit should be more pronounced especially if it takes like 100+ damage off you.
This imo is the main cause why people hack so much especially talking about radars and wallhacks = they don't want to pay attention to the game + audio is sub-optimal => get tired of getting jumpped on by enemies => download hacks.
It is sad to see that AAA game can't manage something that e.g. Quake 3 managed to solve perfectly imo 25 years ago! I still remember how with fine-tuned audio settings even with that time hardware you could perfectly place prefire shot with railgun...oh good old days. (good old for me, newer generation would probably be triggered by such game these days = too hard, too sweaty :D)