Incorrect country dialling format

When I was on a trip to the US recently I used the dual sim card function on my iPhone 12 Pro for the first time. I inserted a physical US sim card and used it as the primary number while travelling whilst maintaining my Australian eSIM as the secondary number. When I got home I took out the US sim card and reverted my Australian eSIM to the primary number. This all worked great apart from the change to my phone dialling input. Its a small thing, but it bugs how my phones dialling input is now stuck in US format X(XXX)XXX-XXXX. This is very different to the Australian format and makes me second guess numbers I am manually dialling. All location and regional settings are set to Australia and I cannot work out anyway of changing this back. Does anyone have any suggestions?