Some percentage of free tier people are also paying on other accounts, and some will be lost.

But it’s probably a small amount because SaaS has figured out to basically milk slacktivism. People will complain but pay.

I'd think that's not the main problem -- it's instead fewer new users? Impacting future paying customers

Opportunity cost to an extent: instead of convincing them into becoming paying customers, and having them word-of-mouth promote you, they slip away to a competing service, which they may also indeed decide to pay for.