Agree with SmashedAvacado. Additionally you need to check if the tenancy is considered to already have been passed down once, leaving HA no obligation to continue housing, or rehouse either of you if one of you leaves, regardless of if it could be afforded.
It's common that if one partner leaves or dies, the tenancy is considered to have been handed down (permitted once) to the remainer/survivor and children adult or not have no right to be put on the tenancy or inherit it. (even if disabled.)
20 year old males with up heaved pasts aren't generally known for thoughtfulness and awareness, and their generations expectations and lifestyles are different from their parents. Generally it's a phase and maturity changes it.
But right now his behavior is selfish and unreasonable. He probably doesn't 'think he has you over a barrel' he probably just doesn't think at all!
If you're using housing benefit to pay rent and council tax then he may also be quite detached from his financial situation or obligations to you.
HA properties are often horribly thin walled, so apart from trying to get him to understand a more grown up approach as adults sharing, if he want's to be able to talk in his room, is it worth considering adding sound insulating 'plaster board.' (called acoustic plasterboard) for either his, or your bedroom, or both, if affordable? You can sometimes get it cheap if cosmetically damaged or pre-used. Any way he could pay for this even in increments? You might find he prefers not to need it.
Also is he using a head set that fully covers both ears? I tried my Ds's head set and it turned out I also raise my voice considerably when using it too, especially when being sociable on zoom. Removing it from one ear helped.
It's hard for them to behave entirely as adults when mum's still there demanding certain domestic standards, and not helped by the government and law treating them as not legally liable for their share of rent, bills or council tax, therefore unable to receive help when the pandemic struck, and many were suddenly forced into childhood financial dependence regardless of age or if their parent is able to support them all.
If you don't have lots of space or money to throw at solutions, sharing as a grown up family can be hard work. Listening, (really listening) talking, compromise, and patience, as well as continuing to take a basic interest in their interests (even when it's gaming) are key to establishing something workable when you're sharing but wish it wasn't needed.