This is a two fold issue. I’m not sure what they did in 13 but I’ve noticed during my normal use of browsing the web, forums, scrolling things (apps), the lightest touch is activating preview, peek/pop, highlight, stuff that it never did before unless I intentionally pressed harder (I also feel...
I find the peek and pop features in Mail, Safari and Messages absolutely useless and I wish 3D Touch in these apps were allocated to more useful functions. I have set up a poll because I'm interested in whether some people actually find it useful.