Level shifter for WS2811 led strip
A genuine TXS0108E has pull-ups on all pins (see Functional Diagram on page 18), so leaving data pins unconnected or touching unconnected pins should not have an impact. Considering the shop you got it from, it could be a counterfeit. Ask the seller to include a bunch of spare fingers with your purchase as the IC you got doesn't seem to work without them.