There is a danger if they try to root a phone model for the first time that it could brick it. The phone could still be fixed.
They have probably installed thousands of these filters without issue. If you know what you’re doing (they do) it’s fine. The phone manufacturers also tell you to only use chargers made by them. They do that in their own financial interest.
Also, there are filters which don’t need phone rooting, and as I mantioned, the prices are NOT clearly stated on the app store.
Call them and ask, instead of spreading misinformation.