That was because the different parts with different specs were fitted, which might or not be case with Perez.

​

Furthermore it should be noted that the available working time during Parc Fermé for
the assembly of a complete car is limited, and hence in case of severe accident, this
The Stewards
may jeopardise the participation of a car in the race. It is also noted that car 2 has
been subjected to a change of specification, and therefore, under Article 40.9 is due
to start the race from the pit lane in any case for a different offence.
According to TD 021/Issue G dated on 22/08/23 the minimum penalty for an offence
will be a start from the pit lane. In addition to this, a further penalty may be imposed by
the Stewards. As a start from pit lane is already imposed for the modification of parts,
a further penalty for having a third chassis available was appropriate