Screen goes black randomly with HDMI Splitter

I own a BenQ GL 2250 and a graphic tablet : the Kamvas 13 by huion.
I needed to be able to plug them both at the same time on my PC but I only had one hdmi cable, so I bought an Hdmi Splitter : https://www.amazon.fr/gp/product/B07DW2445X/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

I have a nvidia gtx 970

Both monitors (the BenQ and my onscreen tablet) plug in just fne, they are both recognised as one monitor (which was to be expected) but here is the issue :

the screen goes black randomly and turns back on normal, he flickers if you will.

I could handle this but the real problem is that whenever I do something tha would normally cause my screen to turn black for one second (windows + D for example), both monitors start to show no signal until they do or until I turn on and off my tablet.

And most importantly, will this possibly damage my graphic Tablet ? It was quite expensive for me and I wont be able to get another if it breaks

Thank you in advance