fs corruption

solo ~ # fsck.fat -v -V -a -t /dev/sda2
fsck.fat 4.1 (2017-01-24)
Checking we can access the last sector of the filesystem
0x41: Dirty bit is set. Fs was not properly unmounted and some data may be corrupt.
 Automatically removing dirty bit.
Boot sector contents:
System ID "MSDOS5.0"
Media byte 0xf8 (hard disk)
       512 bytes per logical sector
      1024 bytes per cluster
      6654 reserved sectors
First FAT starts at byte 3406848 (sector 6654)
         2 FATs, 32 bit entries
    393728 bytes per FAT (= 769 sectors)
Root directory start at cluster 2 (arbitrary size)
Data area starts at byte 4194304 (sector 8192)
     98304 data clusters (100663296 bytes)
63 sectors/track, 255 heads
    616448 hidden sectors
    204800 sectors total
Starting check/repair pass.
/EFI/Microsoft/Boot/Fonts
  Contains a free cluster (18247). Assuming EOF.
/EFI/Linux/kernel-4.9.4
  File size is 5968464 bytes, cluster chain length is 5720064 bytes.
  Truncating file to 5720064 bytes.
Checking for bad clusters.
Reclaiming unconnected clusters.
Reclaimed 196 unused clusters (200704 bytes) in 1 chain.
Checking free cluster summary.
Starting verification pass.
/EFI/Microsoft/Boot/Fonts
 Start does point to root directory. Deleting dir.
Checking for unused clusters.
Performing changes.
/dev/sda2: 487 files, 50041/98304 clusters