Yeah this is the reason most probably. After the UI update I had the exact same problem. After 2 days of search for solution I finally found it. When it tries to open with discrete GPU it just blinks and doesn't open. I can only open it with integrated GPU. And you definitely have to use DRI_PRIME=1 argument for every game to open them with dGPU. It is kinda annoying but it's only solution for now until Valve updates it.
Debian not recommends testing for everyday using. You definetely have to look at the site. Afaik it is basically a bad version of unstable that gets slow updates and it is only for testing purposes.
I think your problem is you are using a niche Arch derivative that has a small user base. You should definitely consider using more mainstream distros so you can easily find the help you need until you are comfortable and feel confident with using Linux.
Yeah I've been subscribed to both of them too but like I said I felt lazy to write all of them. Also Honest Guide's content range is broader and video styles are different. But Brick Technology is also good.
NJB is really pro Netherlands but I am kinda okay with that because I really didn't consume any media before that are pro Netherlands so it has a place to join with the pro America, UK and France media I guess.
I don't understand recommending an another company distro to user who is happy with using Fedora but want to change it just because it is a company distro. (They both are actually community projects but let's ignore it for the purpose of this discussion)
Yeah this is the reason most probably. After the UI update I had the exact same problem. After 2 days of search for solution I finally found it. When it tries to open with discrete GPU it just blinks and doesn't open. I can only open it with integrated GPU. And you definitely have to use DRI_PRIME=1 argument for every game to open them with dGPU. It is kinda annoying but it's only solution for now until Valve updates it.