Massive "System Services" downloads over cellular data

HELP! i don't see that this got resolved and i am now having this issue. i've worked with Apple and Verizon and i get odd feedback like "we've never seen this before" but also "that's normal." these are contradictory statements! i need help. my situation is potentially wonkier than those described above, or others didn't review the spreadsheets of data usage.

on June 1, 2020, ALL 4 lines on our family plan started having System Services use a lot of data 4 times a day. this literally was not happening through May 31, 2020. my sister and i live alone, my parents live together. we are all on wifi almost 100% of the time since we are all at home due to the pandemic.

when i identified the increased data usage, i downloaded the data use spreadsheets from verizon. upon review, i found that the 4-times-per-day System Services data usage is the ONLY data our phones used. the information below shows the ONLY data used on those days.

also note the trend of:
9:31 AM / 9:31 PM
3:32 AM / 3:32 PM

DATE ----------TIME-------KB
08/03/2020 09:31 PM  588970.76
08/03/2020 03:32 PM  107499.42
08/03/2020 09:32 AM  3922.82
08/03/2020 03:32 AM  47.23
08/02/2020 09:32 PM  3006.04
08/02/2020 03:33 PM  20275.93
08/02/2020 09:33 AM  140517.67
08/02/2020 03:33 AM  186.57
08/01/2020 09:33 PM  258.62
08/01/2020 03:34 PM  2951.25
08/01/2020 09:34 AM  484.02
08/01/2020 05:56 AM  31.74
07/31/2020 11:56 PM  207766.12
07/31/2020 05:56 PM  183855.87
07/31/2020 11:57 AM  226.21
07/31/2020 05:57 AM  647.05
07/30/2020 11:57 PM  31.81
07/30/2020 05:57 PM  627.63
07/30/2020 11:58 AM  57769.69
07/30/2020 05:58 AM  57.92

i have done the assessments to reset statistics on all phones.

we did not all download the same app or manually change the same setting, or all update to a new iOS at midnight on June 1st. at least 2 of us do not allow autoupdates of iOS. i recently got my dad a new phone. it continues to happen on his line.

we do not have an unlimited data plan and we are running out of data each month.

I’ve found the solution to this question at discussions.apple.com

Here is the link:
Documents & Sync High Data Use Despite Turning Off iCloud Sync & Using Low Data Mode

"I found the same thread on Stack Exchange! 
After exhausting my troubleshooting ideas, I got in touch with Apple Support.

They connected me to a Senior Engineer who remoted into my phone to help diagnose a fix. 

Ultimately what fixed it was

1. logging out of iCloud,

3. doing a hard reset of the phone while logged out,
5. then logging back in to iCloud.

I'd tried those things in different orders, but I had not tried a hard reset WHILE logged out of iCloud.

Since logging back in on Wednesday night, my data usage has returned to normal. 3 total MB used over the last three days, CONSIDERABLY better than the 200-300 MB/day it was using. So if you're having this problem, I recommend trying this fix!"