broken encoding on fly machine / suspect fly proxy?

I don’t know exactly how to investigate this issue, but I know is related to fly.io

I have an app that returns data using the following content type application/json; charset=utf-8

And is usually working fine, but suddenly it starts returning all unicode characters with ?

I checked everything from the database to the app and it all works fine.

I restarted the fly machine and it started working again. so now, every time I get the same behavior I restart the machine and it gets fixed.

I suspect it may be related to this, but not sure content-encoding: zstd

I’m setting ‘content-encoding’, ‘none’ for now to disable compression and test if that fix it

What browser and version you using? Are you using cloudflare? They’ve had a few minor kinks, eg Cloudflare Status - Issues with Zstd compression

Added proxy

no, I’m not using cloudfare.

I tested on Firefox Desktop, Chrome and Firefox Android. all same result.

so the app has been working without issues after I disabled compression. the error must be related to the proxy. maybe when compressing json is ignoring the defined charset?
although is strange it works after a restart.