The largest discounts on Steam are observed during the summer and winter sales, but the summer one is considered to be the best. In the summer sale, players can purchase relatively new games at extremely high discounts.
The big Steam Summer Sale 2019 starts on June 25, 2019 at 21:00 AM PDT! You have the opportunity to buy games with 50%, 60% and 70% discount!
List of games for Linux: https://store.steampowered.com/linux.
The sale will last until July 9, 2019. Do not miss.
Source: linux.org.ru