This isn’t a bug, this might be an actual sound design issue.
I won’t get too much into technical details here, but sound is really just pressure waves.
Your game might suffer from phase cancellation.
When two sounds play that both take up the same frequency, they sometimes fight for space.
This typically happens a lot with explosions and gun firing sounds because they’re loud and can have many frequencies.
Explosions might have lots of bass in them which can drown out other low-pitched sounds.
So sounds of your car engine (which are also often low and deep) can get drowned out by the sound of a distant explosion.
The solution?
Make space! You’ll have to decide which sounds take priority over others if you want to keep it simple.
Take a look at this:
https://create.roblox.com/docs/reference/engine/classes/AudioEqualizer
https://create.roblox.com/docs/reference/engine/classes/Sound#SoundGroup
Roblox has a bunch of stuff which you can use to process sounds with.
Try reducing the bass in some sounds or other various effects and see what it does with the sound.
A basic understanding of audio mixing is heavily recommended.