Tonight, f.lux used 116 MB of data

[Jahus]

Here are screenshots from GlassWire:

I suppose it's a bug since I see no reason why flux would use that much data.

Version 4.76

[herf]

Interesting - this is the "certificate revocation list" from Comodo. This is the "browser" (here the internet explorer code we use to check for updates) making sure our SSL certficate has not been revoked.

Usually this bandwidth cost would be "shared" among multiple apps/websites, but in this case, f.lux made the first SSL request with this registrar, so IE pulled the CRL down also.

https://blog.cloudflare.com/the-hard-costs-of-heartbleed/