Time Machine backups taking long, after macOS Sonoma update on my MacBook.

Ever since I upgraded my M1 Macbook Pro from the immediately previous Mac OS version to Sonoma, I have had nothing but problems using Time Machine to perform backups on an external SSD. No issues at all prior to Sonoma doing incremental backups for about one year - took about 20 minutes per incremental backup. My first backup attempt using Sonoma, I gave up after 3-1/2 hours when Time Machine reported 3 hours still remaining. Tried a second time while Time Machine had been running for some time and while on the phone Apple Support , gave up after 2-1/2 hours. I had other tasks to attend to. On a third attempt at Apple Support's recommendation, I let it run to see if it would error off. It did not error off, but this time it took about 3-1/2 hours for an incremental backup. Apple Support gave me a follow up call after the last backup completed at 3+ hours. They requested that I reinstall Sonoma and run Time Machine again and report back. Spoke with Apple Support after the reinstall of Sonoma and Time Machine backup completed. Time Machine backup completed in about one hour. Apple Support then requested that I initiate a new incremental backup while on the phone with them - an absolute disaster followed. I shared that Time Machine was reporting over 17,000 changes after about 30 minutes of idle time, with no activity, no browsing, no nothing , just sitting idle while charging. While on the phone with Apple Support again, Time Machine reported an estimated backup time of 10 hours! Terminated the backup and communicated such to Apple Support. As a software PM, there is no doubt in my mind that there is a significant flaw in Apple's Mac OS Sonoma and the Time Machine app. It bothers me that I have also wasted many hours over several days trying to resolve this issue. I have zero confidence that my Time Machine backups are correct and usable.

[Re-Titled by Moderator]