Data usage meter metering about 2500x more than I am using - Solved

Edit: Solved. My work computer was upgraded to MacOS Sequoia last week and process idleassetsd was using GBs per minute (usage went up by about 700GB yesterday). Switching wallpapers and screensavers to static images stopped the usage. Sorry for blaming Xfinity! It still would have been easier to diagnose with more granular metrics!

OP below
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I started getting usage warnings last night (90% usage at 7:55pm). This is unusual as we are usually under 600GB by month end.
I turned on traffic statistics on my router at 10:19am - Xfinity usage meter said I had used 1263GB at that time (103%). By 12:04pm this had increased to 1285GB, but my router shows about 4MB used:

Traffic Statistics List

IP Address MAC Address Total Packets Total Bytes Current Packets Current Bytes Current ICMP Tx Current UDP Tx Current SYN Tx Modify
10.0.1.21 [Edited: "Personal Information"] 24,861 3,363,994 0 0 0 0 0 
10.0.1.10 [Edited: "Personal Information"] 949 81,963 0 0 0 0 0 
10.0.1.13 [Edited: "Personal Information"] 1,892 314,648 0 0 0 0 0 
10.0.1.25 [Edited: "Personal Information"] 3,250 288,760 3 230 0 0 1 
10.0.1.3 [Edited: "Personal Information"] 2,897 454,263 8 596 0 0 0 
10.0.1.17 [Edited: "Personal Information"] 474 48,073 0 0 0 0 0 
10.0.1.2 [Edited: "Personal Information"] 266 25,199 2 170 0 1 0 
10.0.1.14 [Edited: "Personal Information"] 729 65,070 3 210 0 0 0 
10.0.1.7 [Edited: "Personal Information"] 6 440 0 0 0 0 0 
10.0.1.34 [Edited: "Personal Information"] 11 714 0 0 0 0 0 
10.0.1.23 [Edited: "Personal Information"]14 1,080 0 0 0 0 0 

Current metered usage is at 1338GB (12:34pm). Router was restarted (due to a power outage), so tracking it from 12:34pm.

Something is definitely up with the metering.