How is income determined to be taxable before a Form 1099-K is issued?

I'd like to know if there is a way in which income is determined to be taxable before it is reported on Form 1009-K.  I ask because many people use payment apps to transfer money for many different reasons outside of side gig or business related transactions (ex: to send a family member a birthday gift).  Will you automatically receive a Form 1099-K if you meet the income threshold and even if the income is non-business related?