Firefox should be limiting the size of "File System" or clearing it automatically.
In this case, "Clear browsing data on exit" in chrome://settings/privacy may be useful.
As I know, there is no native way to block writing to "File System" in Chromium.
In this case, "Clear browsing data on exit" in chrome://settings/privacy may be useful.
As I know, there is no native way to block writing to "File System" in Chromium.