Question: what will happen if the certificate chain of backend server became invalid?

we have configured ssl both on haproxy and the backend server, suppose like this

server sab1 10.10.10.100:443 ssl verify none check check-ssl
server sab2 10.10.10.101:443 ssl verify none check check-ssl

there is something that caused the certificate chain of backend servers to be invalid, what will happen ( no need to change certificate chain on haproxy side) ? will the https requests from haproxy become to be unresponsible ?
i just know the the direct visit to backend server will be in risk.