[sokoloff]

That article contains a "real income growth since 1967" table (about halfway down, on the right).

All quintiles show growth, with the 4th quintile (20-40th percentile) showing the lowest growth at +31.1% and the 5th quintile (lowest 20%) showing a similar +34.2% across that period of multiple decades.

That's indeed "essentially flat, but still slight growth".

[fundad]

"real income growth" does not account for health care and housing costs (except for people who own their home)

[cheriot]

Their incomes are growing slower than essential expenses like childcare and healthcare...