I googled for one example SoFi Select 500 ETF
Low cost We’ve waived management fees* on our SFY ETF so more of your
money is invested in the market.
looking in the fine print:
The Fund’s investment adviser, has agreed to waive its Management Fees
for the Fund until at least June 30, 2023.
It also includes this comment: (I added the bolding)
There is no guarantee that the Fund’s investment strategy will be
successful, investments in REITs involved unique risks. Securities in
the real estate sector are subject to the risk that the value of their
underlying real estate may go down. Shares may trade at a premium or
discount to their NAV in the secondary market and fund’s holdings and
returns may deviate from those of its index. These variations may be
greater when markets are volatile or subject to unusual conditions. A
high portfolio turnover rate increases transactions costs, which may
increase the Fund’s expenses. The Fund is new and has a limited
operating history. The Fund is passively managed and attempts to
mirror the composition and performance of the Solactive SoFi US 500
Growth Index. The Fund’s returns may not match due to expenses
incurred by the Fund or lack of precise correlation with the index.
You can lose money on your investment in the Fund. Please see the
prospectus for a discussion of the Fund’s risks.
Note the fund is new, and there are other expenses besides the management fee.