I’ve been looking at posts from 2013 / 2018 where people are showing codesnippets where they multiply the horizontal velocity like this:

   rb2d.velocity = rb2d.velocity.x * 0.9;

When I attempt to do that in the most recent version of unity I get this error:
161788-aantekening-2020-06-12-191114.png

Is there any way to multiply the horizontal velocity?

ok…

vector2 v = rb.velocity;
v.x *= 0.9f;
rb.velocity = v;