Upload Speeds Suddenly Low

My upload speeds have been consistently about 35Mbps, but as of a few days ago, they are less than 5Mbps. Download speeds remain consistently above 500Mbps. I have a 1Gps Xfinity plan.

I've rebooted the modem (ARRIS T25) multiple times, checked the connections for tightness, and ran the Xfinity online troubleshooting tests. I've attached a screenshot of the modem's upstream power levels.

Appreciate your thoughts on this. Nothing has changed on my end that's under my control. Has Xfinity possibly throttled upload speeds? Thank you.