IPad always uses palm when drawing with pen?

Hello first of all,

I have an older iPad from 2014 and wanted to buy an Apple Pencil because it still works perfectly. After doing some research, however, I discovered that it only works with models from 2018 or newer, so I bought a cheaper version that works.

The pen itself works perfectly, but when I write with my hand on the tablet, the iPad doesn't recognize the pen. Is this because the iPad is old or the pen is a cheap version, or is there something I can change in the settings?

The second question that comes to mind is why the Apple Pencil doesn't work but a cheap version does (it's also an active stylus).

thank you in advance