The slow charging issue appears to be related to the type of battery technology in the car. Teslas are 400 volt while others are 800v. According to the article 800V cars are throttled to about 50kwh. Cars that have 400V architecture don’t have the issue..
My Hyundai Ioniq 5 can take 350kW at CCS chargers. But with the Tesla Supercharging stations now offering CCS too (as well as their older standard for Tesla cars), the charger limits CCS to only 50kW or so.