FWIW, this is what I'm seeing: https://imgur.com/a/pbR0SCH

Please stick to a font already in my browser. My network is slow and webpages sometimes get stuck loading; the resources in your page took 40 seconds to load and your font didn't even load yet.

Turning this clause off in your style sheet turns off that awful st ligature:

font-feature-settings: "liga", "dlig";

So just remove that clause from your stylesheet and you'll be rid of that ligature.

I like ligatures when they're used well, but that one is just incredibly distracting.

Shame the advice is to turn them off completely...

Testing a big more, just dropping "dlig" from the feature settings declaration turns off the awful st ligature. So they don't have to 'all' be turned off to get rid of that one. What I don't know is what other ones get turned off by dropping "dlig" from the declaration.

I have no problems with the current one apart from the s and t connecting like that.