connector for 25Amps
Your decision to route that amount of power using an internal layer is poor choice IMO. From what I understand, the via in which the component lead is seated, is the bottleneck connection.

Please excuse the crudeness of the following depiction - I tried to emphasize how soldering through-hole leads on outer layers makes sense. It allows larger mass of solder to be in the way of current, therefore decreases resistance.

(Amount of arrows indicates current cross section/conductance)






simulate this circuit &ndash; Schematic created using CircuitLab

There's one more thing to consider. It's not always guaranteed, that your plated holes will be 100% filled with solder. In such case, the situation is even worse, as the currents have to travel up and down the via's plating.



Bottom line is:

Solder high-current leads to outer layers and if needed, provide heavy via stitching to a layer of choice afterwards.