The regulation is this one - mainly (ii) as (i) will never apply in any domestic installation and (iii) which is not shown requires a device to disconnect the supply if voltage between earth and the protective conductor exceeds 70V.
There is an exception where all of this can be ignored as seen in the text image, with the useless' reasonably practical' part. However that has been deleted in the 18th edition, so very shortly one of the three items will be required if using a TN-C-S supply.
Installing EV systems as TT is the most common option, with their own electrode just for the EV installation and not connected to the TN-C-S earth at all. That avoids all of the below, and the electrode just needs to comply with the normal requirements for any other TT installation.
View attachment 150404
The problem with (ii) is that the electrode has to be of very low impedance to be a viable option.
This is the calculation, Ra being the maximum sum of the electrode and protective conductor resistance:
View attachment 150405
with the other items being Uo supply voltage (230V) and the current Iinst being the full load of the installation including the EV charger. 50 amps would be a conservative estimate, given that the charger is 30 and another 20 for whatever might be in use elsewhere. In many cases it could be far higher.
However with a 50 amps load, the required resistance is 2 ohms, something which will be near impossible with any electrode.
Even with a totally implausible and useless 10 amps, the resistance is a maximum of 10 ohms - still rather difficult and not going to happen with a single rod.
Therefore for the original query, they have either got an electrode attempting to comply with 722.411.4.1(ii) which almost certainly does not, as it's impedance will be far too high.
Or it was intended to be a TT installation (as is most commonly done), and it's all gone wrong because it's connected to the TN-C-S earth as well.