Which of the following statement is not true for the reaction given below?

$[\mathrm{Cu}{\left({\mathrm{H}}_2\mathrm{O}\right)}_4 {]}^{2+} + 4{\mathrm{NH}}_3 \to [\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_4{]}^{2+} + 4{\mathrm{H}}_2\mathrm{O}$

It is a ligand substitution reaction

NH₃ is a relatively strong field ligand while H₂O is a weak field ligand

[Cu(NH₃)₄] ²⁺ , has a tetrahedral structure and is paramagnetic

During the reaction, there is a change in colour from light blue to dark blue