Valve's platform recently detailed its policy on advertising content in video games. Some practices are authorized and others prohibited. Productions that do not respect these conditions will obviously be banned.
Thus, Steam explains that real-world product placements, paid advertising outside of Steam, and cross-promotions (bundles, promotional events) are permitted.
However, developers are not allowed to use advertising as a business model for their game. For example, it is forbidden to hide gameplay aspects or rewards behind advertising, as can be the case on mobile devices. To publish their title on Steam, studios must remove these elements.
Additionally, developers should not charge other developers for access to Steam features. This includes promotional pages, bundles, franchise pages, etc.
https://partner.steamgames.com/doc/marketing/advertising