Vidéo perd de la qualité lors de la mise en ligne sur youtube

youtube la qualité de la vidéo mise en ligne est faible

When you upload a video, it will initially be processed in low quality.
This process helps you complete the upload process faster. 
When the upload flow is complete, your video will be available 
to stream in low quality, on a wide variety of devices.

Higher qualities, such as 4K or 1080p, can take more time to process.