Is Formula Overridden LAMBDA Function

IsFormulaOverriden.lambda

/*
Name: Is Formula Overridden (IsFormulaOverridden)
Description: Checks whether the cell is either not a formula or
    a formula that contains no letters (ie: =123.45+678.90).  Can
    be used with conditional formatting to highlight when users 
    hardcode numbers over your formulas.
Author: Excel Robot (@ExcelRobot)
Category: Auditing
*/
IsFormulaOverridden=LAMBDA(Cell,
    LET(
        IsFormula, ISFORMULA(Cell),
        Formula, FORMULATEXT(Cell),
        Characters, UPPER(MID(Formula, SEQUENCE(1, LEN(Formula), 1), 1)),
        LettersOnly, IF((CODE(Characters) >= CODE("A")) * (CODE(Characters) <= CODE("Z")), Characters, ""),
        HasNoText, LEN(TEXTJOIN("", TRUE, LettersOnly)) = 0,
        IsOverridden, IF(IsFormula, HasNoText, TRUE),
        IsOverridden
    )
)