Instagram overrides my sound preferences

I have always kept my phone permanently muted - i.e. the switch on the side is set to off. This meant that when I scrolled through insta there was no sound (unless I clicked on a post by choice to turn the sound on). This works fine. But now when I watch the reels in my feed the sounds comes on automatically and I can only turn it off by lowering the volume (which of course means I have to turn it back up for listening to music etc - or worse if I forget I was playing music when I go back to insta I get noise that don't want or need).

I have two questions:

Is there a solution to this other than deleting instagram?

If not then

Why does Apple seemingly allow some app providers to override the express preferences of the users?

Mute means mute surely?

Would welcome everyones thoughts