[avian]

It's not a simple text encoding. Almost all byte values are present with an approximately uniform distribution. No strings of 2 bytes or longer repeat in the sequence. There is no apparent structure if you show the data as an image.

If it's not just random junk, it looks non-trivial to me (which doesn't mean anything in case this is someone testing their home-brew encryption). 836 bytes is very little to work on with next to no context.

Also, from poster's user name:

https://en.wikipedia.org/wiki/Hobson%27s_choice_(disambiguat...

[Hobsons_Choice]

I can assure you it's not random junk. The small size is due to the 2000 byte limit. I would be pleased to provide a larger file to work with.