Color change on encoding

[Selur]

using latest ffmpeg from: https://www.gyan.dev/ffmpeg/builds/ also shows the problem (both with 'master' and 'release')
FFmpegs changelog does not hint to something that should do this.

Think I got, it seems like "-colorspace bt709" now need to be added as input parameters too if pipe input is used.
=> I'll look into it