Kevin Federline says Britney Spears is raising tons of red flags since her conservatorship ended ... and he says her sons and family are alarmed with what they're seeing from her.

Britney's ex-husband joined us on "TMZ Live" Wednesday and we asked him if he thought it was a mistake to end the conservatorship.

Kevin says everyone in the family -- including Britney's two sons Sean Preston and Jayden James -- are concerned for her well-being and he says his new memoir, " You Thought You Knew ," is a cry for help to gain support for Britney and their kids. Getty

K-Fed says folks need to read his book to truly understand his thoughts on the conservatorship ... but he says the boys want their mom to be around for years to come and want a relationship with her.

Kevin sa

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