Regarding whether ESXi hosts are automatically disconnected and reconnected when ESXi's certificate expire.
ESXi 7.0, ESXi 8.0
When an ESXi host's certificate expires, it will not be automatically disconnected and reconnected; you must manually disconnect and reconnect to update the certificate.
Japanese KB: ESXi ホストの証明書が期限切れとなった場合に自動更新されるかどうかについて