Steam Cloud Sync will let players switch seamlessly between Steam Deck and PC

gamesradar.com:

Steam Deck developer Valve has said that it is improving Steam Cloud Sync to make it easier to switch between its upcoming handheld and PC. 

In a post shared to Steam, Valve said: "As part of the ongoing work to support Steam Deck, we added a new Dynamic Cloud Sync feature to Steam Cloud. This feature allows players to seamlessly move between Deck and PC instances of the game without needing to worry about exiting the game on the Steam Deck." 

The reasoning for this is explained further down the page, as Valve says: "We anticipate that users will frequently suspend their Steam Deck without exiting the game, as is common with other hand-held gaming devices." The post continues, "with Dynamic Cloud Sync, if they then choose to play on another device (whether a PC or another Steam Deck), their progress will be there waiting for them."

According to the post, the new Dynamic Cloud Sync will use Steam to automatically upload all modified save game data to the Cloud prior to the Steam Deck entering sleep mode. This means that players can seamlessly resume their game on any PC, laptop, or another device. Not only this, but Steam will apparently also automatically download any save game changes when Steam Deck users wake up the device. 

As the post says, Steam Deck owners aren’t required to use the feature however Valve recommends they do so "to give players the best experience possible." 

If players decide not to use the service, however, Steam will instead track when save game data has changed on the Steam Deck but "any user who suspends their Deck while your game is running and then tries to resume that game on a different device, will be prompted to first return to their Deck to close the running process or continue without