Incorrectly claims to not be a PNG file
Using eog 3.38.0 from Debian Sid/unstable, Eye of GNOME complains about a PNG file I was sent (edited with Photoshop?), but Firefox is able to display it just fine.
$ hexdump -C image.PNG | head
00000000 ff d8 ff e0 00 10 4a 46 49 46 00 01 01 00 00 d8 |......JFIF......|
00000010 00 d8 00 00 ff e1 00 74 45 78 69 66 00 00 4d 4d |.......tExif..MM|
00000020 00 2a 00 00 00 08 00 04 01 1a 00 05 00 00 00 01 |.*..............|
00000030 00 00 00 3e 01 1b 00 05 00 00 00 01 00 00 00 46 |...>...........F|
00000040 01 28 00 03 00 00 00 01 00 02 00 00 87 69 00 04 |.(...........i..|
00000050 00 00 00 01 00 00 00 4e 00 00 00 00 00 00 00 d8 |.......N........|
00000060 00 00 00 01 00 00 00 d8 00 00 00 01 00 02 a0 02 |................|
00000070 00 04 00 00 00 01 00 00 04 7b a0 03 00 04 00 00 |.........{......|
00000080 00 01 00 00 04 a6 00 00 00 00 ff ed 00 38 50 68 |.............8Ph|
00000090 6f 74 6f 73 68 6f 70 20 33 2e 30 00 38 42 49 4d |otoshop 3.0.8BIM|