Try this code and let me know if it works for you. You will need to replace the fieldIds in the first 6 lines of the code.

const expenseClientNameId = { fieldId: 26 };
const expenseTypeId = { fieldId: 29 };
const expenseAmountId = { fieldId: 31 };

const clientSummaryTableId = { fieldId: 27 };
const clientSummaryClientNameId = { fieldId: 28 };
const clientSummaryAmountId = { fieldId: 30 };

// Any time the expense client name changes, we need to update the client summary table
LFForm.onFieldChange(async () => {
  // get unique client names and sum amounts
  let summaryClientNameList = {};

  for (let i = 0; i < LFForm.getFieldValues(expenseClientNameId).length; i++) {
    const clientName = LFForm.getFieldValues({
      fieldId: expenseClientNameId.fieldId,
      index: i,
    });
    const amount = LFForm.getFieldValues({
      fieldId: expenseAmountId.fieldId,
      index: i,
    });
    const type = LFForm.getFieldValues({
      fieldId: expenseTypeId.fieldId,
      index: i,
    });
    let clientAmountInSummary = summaryClientNameList[clientName] ?? 0;
    if (type === 'Client Gift' || type === 'Client Entertainment') {
      clientAmountInSummary = clientAmountInSummary + amount;
    }
    summaryClientNameList[clientName] = clientAmountInSummary;
  }
  // separate the client names and amounts into two lists
  const expenseClientNameList = Object.keys(summaryClientNameList);
  const expenseAmountList = Object.values(summaryClientNameList);

  // update the summary table to have the same number of rows as unique client names
  const curRowCount = LFForm.getFieldValues(clientSummaryTableId).length;
  if (curRowCount < expenseClientNameList.length) {
    await LFForm.addRow(
      clientSummaryTableId,
      expenseClientNameList.length - curRowCount
    );
  } else if (curRowCount > expenseClientNameList.length) {
    await LFForm.deleteRow(
      clientSummaryTableId,
      ...Array.from(Array(curRowCount - expenseClientNameList.length)).map(
        (_, i) => curRowCount - i - 1
      )
    );
  }
  // update the client name fields and amounts in the summary table
  await Promise.allSettled([
    LFForm.setFieldValues(clientSummaryClientNameId, expenseClientNameList),
    LFForm.setFieldValues(clientSummaryAmountId, expenseAmountList),
  ]);
}, expenseClientNameId);