Here's some even stronger support. I would put this ahead of the statement from Publication 501. The Standard Deduction Worksheet for Dependents on page 34 of the IRS Instructions for Form 1040 says the following.
"Earned income includes wages, salaries, tips, professional fees, and other compensation received for personal services you performed. It also includes any taxable scholarship or fellowship grant. Generally, your earned income is the total of the amount(s) you reported on Form 1040 or 1040-SR, line 1z, and Schedule 1, lines 3, 6, 8r, 8t, and 8u minus the amount, if any, on Schedule 1, line 15."
