New
#1
It's just a warning that it's over 90% full. It's a tiny partition anyway without a drive letter.
That looks like the recovery partition. You can use MiniTool Partition Wizard to peruse its contents. Yours does seem rather full for some reason. I've copied the contents of my recovery partition for the FCU below. Mine was expanded to 924MB in the FCU and is now 45% used
Attachment 162342