A higher quality sensor will mean less noise in the captured image (especially with poor lighting), so the compressed stream will spend more bits on encoding yo

A higher quality sensor will mean less noise in the captured image (especially with poor lighting), so the compressed stream will spend more bits on encoding you and fewer bits on encoding artifacts. A better lens will reduce distortion and aberration. A larger sensor combined with a large aperture lens will enable a shallow depth of field, so your face can be in focus while the backdrop of your messy home office is out of focus—again helping spend your precious upload bandwidth on the details you want to be transmitting. 4Mbps is nowhere near low enough to level out all the differences between a crap camera and a great camera. With modern codecs, 4Mbps is actually quite a lot of room to work with; Zoom specifies a requirement of just 3Mbps for group video calls at 1080p, and even Twitch only supports up to 6Mbps.