This is super cute, but unfortunately it's currently both misconfigured and broken. Very easy fixes though.

Firstly, it's eyebrow-raisingly slow. A quick network check shows everything is capped at 100kbps download. For PNG images that translates to a hitch-y 2-3 second pause.

Secondly, the slowness is amplified to the point of "this needs fixing" by the total lack of caching. Everything pauses every time the image loads.

Thirdly,

  $ wget -O- https://httpraccoons.com/jpeg/100 | md5sum
  ...
  Length: 530755 (518K) [image/jpeg]
  ...
  9a7aa269111ca315277bbec79bfab5c1

  $ wget -O- https://httpraccoons.com/100 | md5sum
  ...
  Length: 530755 (518K) [image/png]
  ...
  9a7aa269111ca315277bbec79bfab5c1

It's changing the mimetype but serving the same image!

Critically, besides these issues, this is perfect and fit for purpose :)