I might have it wrong, I think I found it when I created S-corp, not LLC, but assumed it would be the same
Here's something the IRS says:
Reasonable compensation
Because an officer of a corporation is generally an employee with wages subject to withholding, corporate officers may question what is considered reasonable compensation for the efforts they contribute to conducting their trade or business. Wages paid to you as an officer of a corporation should generally be commensurate with your duties. Refer to "Employee's Pay, Tests for Deducting Pay" in
Publication 535, Business Expenses for more information. Public libraries may have reference sources that provide averages of compensation paid for various types of services. The Internal Revenue Service may determine that adjustments must be made to the income and expenses of tax returns for both the corporation and an individual shareholder if the officer is substantially underpaid for services provided.