13.2.1 Time Machine won't complete a backup

2023 14" MBP M2 Ventura 13.2.1

Time machine worked flawlessly for 2 weeks, then I updated from 13.2 to 13.2.1 and has been unable to complete a backup - either initial or incremental - on multiple external drives.

Drives are connected directly, are new, swapped cables, etc. Did function flawlessly for the first two weeks when I bought this Mac.

Formatting is correct, wiped external multiple times, first aid, deleted any potential 3rd party conflicts, tried running TM in safe mode. Tested external drives on identical Mac running 13.2 and Time Machine flawlessly completed initial and incremental backups.

Cannot find "in progress" file to see if thats the issue.

Time Machine cannot complete a backup on my mac and issue seems exclusive to mine, only difference in specs between mine and other office computers is that I am the only one who updated from 13.2 to 13.2.1

Suspect 13.2.1 is the issue, but cannot figure out why.

Finder was not working at all - could not find any files. Indexing issue? - disabled and re-enabled indexing/spotlight - Finder now working but no effect on TM.

Apple support has been unable to solve in hours of attempts together.

Symptoms:

TM prepares and begins, but is very slow (2MB/second), eventually bogging down to a standstill at between 47-67% of the (approx 6GB incremental) backup.

Can anyone help? (pretty please!)

Aaron