Consider the following system of quadratic polynomials $f_1,...,f_n \in \bar{\mathbb{F}}_2[x_1,....,x_n]$ :
$f_1 (\bar{x}) = x_1 + x_n^2 + q_1$
$f_i(\bar{x}) = x_i + q_i$ for $i \in \{2,...,n-1 \}$
$f_n(\bar{x}) = g(\bar{x}) + l^2$
where $q_1,...,q_n$ are homogenous quadratics and $x_n^2, x_1^2 \notin supp(q_i)$ for $ i \in \{1,...,n-1\}$. Here $l$ is homogeous linear polynomial and $g(\bar{x}) = \sum_{i \neq j} a_{i,j} x_i x_j$.
Suppose for some $1 \leq k \leq n$, we know $f_n + A(f_1,...,f_{n-1}) = x_n^{2^k}$ mod $\langle \bar{x} \rangle^{2^k + 1}$, where $A \in \bar{\mathbb{F}}_2[y_1,....,y_{n-1}]$.
Can we say that $l \neq 0$?
Any help would be appreciated.