@James268064665dsv – You can also try this script, which will change all artboard names in a single run (a single history step undo is included).
/*
Rename All Artboards to Artboard Dimensions.jsx
https://community.adobe.com/t5/photoshop-ecosystem-discussions/automatically-change-artboard-name-to-artboard-dimensions-in-pixels/m-p/13299226
Stephen Marsh, v1.0 - 27th October 2022
*/
#target photoshop
function main() {
app.activeDocument.activeLayer = app.activeDocument.layerSets[app.activeDocument.layerSets.length - 1];
// Loop forward over top level layer sets
// for (var i = 0; i < app.activeDocument.layerSets.length; i++) {
// Loop backward over top level layer sets
for (var i = app.activeDocument.layerSets.length - 1; i >= 0; i--) {
try {
app.activeDocument.activeLayer = app.activeDocument.layerSets[i];
var originalRulerUnits = app.preferences.rulerUnits;
app.preferences.rulerUnits = Units.PIXELS;
// Active Artboard Dimensions, by Rune L-H
var ref = new ActionReference();
ref.putEnumerated(charIDToTypeID("Lyr "), charIDToTypeID("Ordn"), charIDToTypeID("Trgt"));
var artBoardRect = executeActionGet(ref).getObjectValue(stringIDToTypeID("artboard")).getObjectValue(stringIDToTypeID("artboardRect"));
var artBoardRectWidth = new UnitValue(artBoardRect.getDouble(stringIDToTypeID("right")) - artBoardRect.getDouble(stringIDToTypeID("left")), "px");
var artBoardRectHeight = new UnitValue(artBoardRect.getDouble(stringIDToTypeID("bottom")) - artBoardRect.getDouble(stringIDToTypeID("top")), "px");
activeDocument.activeLayer.name = artBoardRectWidth.value + " x " + artBoardRectHeight.value;
app.preferences.rulerUnits = originalRulerUnits;
} catch (e) {}
}
}
app.activeDocument.suspendHistory("Rename All Artboards to Artboard Dimensions", "main()");