Fix system messages to only cover direct update

src/libs/ReportUtils.ts

@@ -2982,7 +2982,8 @@ function getModifiedExpenseOriginalMessage(
 
     // The amount is always a combination of the currency and the number value so when one changes we need to store both
     // to match how we handle the modified expense action in oldDot
-    if ('amount' in transactionChanges || 'currency' in transactionChanges) {
+    const didAmountOrCurrencyChange = 'amount' in transactionChanges || 'currency' in transactionChanges;
+    if (didAmountOrCurrencyChange) {
         originalMessage.oldAmount = TransactionUtils.getAmount(oldTransaction, isFromExpenseReport);
         originalMessage.amount = transactionChanges?.amount ?? transactionChanges.oldAmount;
         originalMessage.oldCurrency = TransactionUtils.getCurrency(oldTransaction);
@@ -2999,19 +3000,22 @@ function getModifiedExpenseOriginalMessage(
         originalMessage.tag = transactionChanges?.tag;
     }
 
+    // We only want to display a tax rate update system message when tax rate is updated by user.
+    // Tax rate can change as a result of currency update. In such cases, we want to skip displaying a system message, as discussed.
+    const didTaxCodeChange = 'taxCode' in transactionChanges;
+    if (didTaxCodeChange && !didAmountOrCurrencyChange) {
+        originalMessage.oldTaxRate = policy?.taxRates?.taxes[TransactionUtils.getTaxCode(oldTransaction)]?.value;
+        originalMessage.taxRate = transactionChanges?.taxCode && policy?.taxRates?.taxes[transactionChanges?.taxCode].value;
+    }
+
     // We only want to display a tax amount update system message when tax amount is updated by user.
     // Tax amount can change as a result of amount, currency or tax rate update. In such cases, we want to skip displaying a system message, as discussed.
-    if ('taxAmount' in transactionChanges && !('amount' in transactionChanges || 'currency' in transactionChanges || 'taxCode' in transactionChanges)) {
+    if ('taxAmount' in transactionChanges && !(didAmountOrCurrencyChange || didTaxCodeChange)) {
         originalMessage.oldTaxAmount = TransactionUtils.getTaxAmount(oldTransaction, isFromExpenseReport);
         originalMessage.taxAmount = transactionChanges?.taxAmount;
         originalMessage.currency = TransactionUtils.getCurrency(oldTransaction);
     }
 
-    if ('taxCode' in transactionChanges) {
-        originalMessage.oldTaxRate = policy?.taxRates?.taxes[TransactionUtils.getTaxCode(oldTransaction)]?.value;
-        originalMessage.taxRate = transactionChanges?.taxCode && policy?.taxRates?.taxes[transactionChanges?.taxCode].value;
-    }
-
     if ('billable' in transactionChanges) {
         const oldBillable = TransactionUtils.getBillable(oldTransaction);
         originalMessage.oldBillable = oldBillable ? Localize.translateLocal('common.billable').toLowerCase() : Localize.translateLocal('common.nonBillable').toLowerCase();