Having more devices is good but if you don't know how to manage them from security perspective then there's no fun and main part is most people have their funds stored on the same device they gamble upon which could turn risky sometimes if you ever click on those phising links.But have not heard about any scam site operating under the name of Rollbit till the moment but still remain safe.
It's better for me to activate 2FA for my account in Rollbit and log in my account on computer to play games. I don't feel safe to login my account on a smart phone that has my 2FA too. It is like I do all things on one device and it's so risky. I perhaps worry a lot about it but prevention and carefulness are better than carelessness.
I do not think it is possible for a website or app to steal your keyboard information, except your device has previously been infected by a malware or virus. The screen resolution could be used by some sites to bring up pop ups in awkward positions (and make the option to cancel so small), where one can easily click to accept some random suggestion mistakenly as they would by clicking with their fingers.
With malwares infected on our devices, they can steal a lot of information on our devices.
It is right to have good behavior on our devices and if we are careful, we are safe but I implied that a more carefulness we have, a more safety we will have.
If we use computer with bad surfing like visiting porn sites, clicking on any link, opening any file someone sent to us, we are not safe too. That computer can not give us more safety than a smart phone.