File this under the list of issues plaguing CD Projekt Red's (CDPR) AAA title Cyberpunk 2077, but apparently, if you craft way too many items in-game, your save file will be irreversibly damaged and you will lose all progress contained in it. This issue started making the rounds on GOG forums a few days ago but has now come under the spotlight due to the company's response.
Much like The Witcher 3, Cyberpunk 2077 also allows players to collect various items to craft new materials for utilization or to sell them for commercial gains. This is a pretty standard mechanic that is a core component of major RPG titles. However, if you do this excessively in Cyberpunk 2077, you will corrupt your save file and lose all progress.
As highlighted in various Reddit and GOG threads a few hours ago, save files are reportedly capped at 8MB. If you exceed this limit - which is very much doable if you like to collect and craft items -, your save file will be irreversibly damaged. This is presented by a warning sign on the save file, saying that "Saved data is damaged and cannot be loaded".
This issue is confirmed to be present on the PC version of the game, and other Reddit threads have indicated that the same happens on console counterparts of the game as well. CDPR has confirmed the problem and stated that:
Unfortunately the save is damaged and can't be recovered. Please use an older save file to continue playing and try to keep a lower amount of items and crafting materials. If you have used the item duplication glitch, please load a save file not affected by it. The save file size limit might be increased in one of the future patches, but the corrupted files will remain that way.
While CDPR hasn't confirmed as to why this limit exists in the game - particularly when this mechanic is such a core component of the "true" RPG experience -, it is likely due to some technical limitation and will be fixed in a future patch, currently anticipated in January 2021. However, until then, players are on their own.