As others already stated remove "Bitdefender".
Rule 1 of Macs is don't install junk. Removing it is the first step in diagnosing an ailing Mac. Often, it's the only step.
disk0 - CT1000P2SSD8 1.00 TB (Solid State - TRIM: Yes)
User-installed SSDs are not a supported hardware modification. It's up to you if you choose to do that, but you're on your own.
Long startup times are a common symptom of third party SSDs. Apple has no interest in testing or evaluating their operation, and certainly will not care if a macOS update (including firmware updates) break them. Many macOS upgrades and some updates have included new startup drive firmware. After modifying a Mac in that manner you must always be mindful of that fact.
Time since boot: About 18 days
Presumably you last noticed that slow startup time 18 days ago? After removing the junk, restart your Mac in the usual manner. Test.
No Time Machine backup - Time Machine backup not found.
You did not ask about it specifically, but if do not back up your Mac, it means the prospect of permanently and irretrievably losing all the information on it does not concern you. Not everyone does, so if you're one of them that's perfectly ok.