The same thing happened to me not recently, and yes, I was about to delete the game and seriously accuse the company of trying to steal private information to sell it to third parties for a few bucks, as many email and social media companies have already done.
The thing is, that is deactivated if you associate your Steam account with a mobile phone Steam Guard, simple and easy, but, already said, they ask for your personal mobile phone. What does Steam and ToS want your phone for? Who knows, better not trust.
In my case, I solved it by sending them a ticket raising my suspicions of their possible illegal businesses and of course, asking them that my Steam account was already sufficiently protected with the normal Steam Guard, the email one. Send them a ticket, it may take a few days, but they will listen to you, believe me, especially if you are serious about it … In other words, let the company care.
We can also wait for some human god to make an addon that at least serves to hide that message that makes the game unplayable.
As easy as it would have been on his part, the typical catcha code message that appears randomly from X to Y hours (they could do it with images, as some websites use) and send that character to jail automatically. And if it is false positive, well, there are tickets for something. But no, we know that this would ruin the artificial strategy of increasing people online on the Steam tables through Popopoint-like events.
Another way that could have reduced the amount of bot and goldseller would have been the simple B2P method (buy your account; it is not the same to ban a free one, than one that requires a minimum payment -which is already impossible at this point, because Many people like me came out chastened by the preorder and the lack of interest of the ToS Staff), incidentally, it would have served to reduce the most illogical restrictions of this game, such as the limit of products to be sold in the Market.
Maybe it’s placebo, but maybe if you finish all the main quests (those with the orange flag) until the last one, the issue will be solved, since in “trade limit title” it appears as a delimiter “you have all revelations”.
Steam Guard was created with the idea of offering a second log in using the device (hardware) itself as a credit card, mostly because of the avalanche of whining idiots who put 1234 passwords on their not clossing sesion accounts or “mypetsname, who knows all my facebook followers” easy to steal in brute force.
Counterproductive method, so what happens if the device that authenticates your log is damaged or lost for some reason? Here begins the laughter, you have lost everything until you prove that X account was yours.