Poor music audio quality when connecting to livestream platforms (ECamm Live & YouTube Livestream)

I’m getting poor audio quality when I connect and perform acoustic guitar/vocal music as a guest on a host’s ECamm Live livestream platform. I’m getting the same poor audio when I attempt to livestream through YouTube Studio. In both cases, the sound is audible, but with noticeable degradation of fidelity (a la early cellphone). Spoken word is not affected; the problem occurs only with guitar/vocal musical performances. Here’s a sample of the audio quality problem I’m experiencing: https://www.youtube.com/live/ggDPZPfo7Hk?si=15gLAsUAaLpvzUXq

This problem occurs regardless of the microphone I use (e.g., MacBook internal mic; external USB mic; high quality condenser mics) and the way in which I connect external mics to the Mac (i.e., multichannel USB mixer; 2-channel USB digital audio interface; direct to USB port). Moreover, the problem does not occur when I record locally to my Mac. Accordingly, I have ruled out the sound input equipment as the source of the audio quality problem.

This problem does not appear to be related to the Mac OS being used. It occurs on Macs running each of the two latest operating systems (i.e., Sequoia and Sonoma). Also, this problem is of very recent vintage; it has arisen only since October 22, 2024, the date of my last show as a guest on my host’s ECamm Live platform. Before that date, I routinely guested on his platform for several years without this audio problem.

Finally, the problem does not seem attributable to the quality of the internet service in my studio (Verizon Gigabit 2.0). I’m connecting via Ethernet, with upload and download speeds typically in the range of 800-900+ Mbps.

Having ruled out my equipment as the source of the problem and given the fact that it occurs on multiple livestreaming platforms (ECamm Live and YouTube livestreaming), I can only surmise that the problem is being caused either by (i) some setting on my Mac of which I am unaware or (ii) some kind of audio throttling imposed by my ISP. 

Can you offer any guidance as to the source of this problem and how to resolve it?