There are quite a few low pressure mixer kitchen taps around,
Did you purchase that tap, do you still have the specification for it, so you can see what the MIN/MAX pressure is
0.1 / 0.5bar is lowish pressure - whereas a lot of those flexible taps need a high pressure.
for example, this is MIN 1bar (OUR mains pressure is around 1.5 , so this is quite high pressure , so i would look for 0.1/0.3 which we used all over the house, although the 0.5 worked OK for us, reduced flow
https://www.toolstation.com/waddesdon-pull-out-mono-mixer-kitchen-tap/p56086
Others can be as low as 0.1bar
have a search for low pressure kitchen mixer taps, huge choice and price range , then look at the specification and MIN pressure - BAR , maybe 0.1/0.3 ish - can always post back here
BUT as stated it maybe a block, EVEN looking at the PTFE , maybe some covering the pipe hole itself & reducing flow.
as mentioned/asked before - FLAT , House How high is the TANK from the TAP