The recent update to 0.15 changed the default font, it now uses your systems default one.
The old default font Inter had ligatures, your systems default font might not have them.
To change back to the old default go to Settings > Appearance > Interface Font and set it to Inter
The Smart Typography plugin by mgmeyers can convert to arrows (among other worthy features) regardless of the typeface you’re using. There’s no need to revert to Inter unless you want to.