I use a 5.1V 2.4A charger and in five months only twice has it charged quickly. It did charge very slowly when I first had the phone in Oct 2020 but now does it just slowly, about 5 hours to charge.
The unit I have has 2 x 2.4A so the background is well over speck as 5v x 2.4A should charge in 1.5 hours max, which as I said did happen twice.
I have been on the case with Fairphone support and am getting nowhere over this issue. More about that elsewhere ~later
Other than that I have a post with more detail.
and a post on Battery Charging Basics.
My advice is not to buy the charger you have mentioned as it may turn out very disappointing. The quick charge comes from a 20V compatible charger that communicates with the phone to provide often 9V at 1A for a period and then drops to slow charging at 90%. My method and the charger you mention are not capable of dynamic communication with the phone.
