Big Sur start up is slow on my iMac 2020 with fusion drive

The only thing I see in the report that is unnecessary is DrCleanerProPlus. There is no reason to ever install or run any 3rd party "cleaning", "optimizing", "speed-up", anti-virus, VPN or security apps on your Mac.  This user tip describes what you need to know and do in order to protect your Mac: Effective defenses against malware and other threats - Apple Community   

Uninstall it according to the deveoper's instructions. Then check to see if you've removed all of the supporting files by downloading and running Find Any File to search for any files with the application's name  and the developer's name in the file name.  For the Dr. Cleaner software you'd do the following search(es): 

1 - Name contains drcleaner

Any files that are found can be dragged from the search results window to the Desktop or Trash bin in the Dock for deletion.

FAF can search areas that Spotlight can't like invisible folders, system folders and packages.  

The report also says you installed Cleaner One two days ago:

2020-12-07 Cleaner One (6.0.7)

However I see no Cleaner One files mentioned in the report. If you installed it and haven't run it don't. Uninstall it.

DrCleanerProPlus.app, Malwarebytes, 32 bit Kernel Extensions: /Library/Extensions MacallyKMDriver.kext (1.0.0d1)

TASCAM_US1xx.kext (3.25rc2 - SDK 10.8), Flash Player (? - installed 2016-12-16), Plus being a Fusion drive with 5400 RPM drive are all contributing to the slowness of computer