After upgrading from v0.1.1 to v0.1.2 of the plugin, I found that there were some styles introduced to the front end that were interfering with my theme. Digging in further, I tracked these to the core common.min.css sheet.

<link rel='stylesheet' id='common-css' href=.../wp-admin/css/common.min.css?ver=5.9.3' media='all' />

I've since replicated this finding on a site with Twenty Twenty Two and no plugins except quickpost 0.1.2.

I haven't experimented with this, but I suspect the issue is the function that's newly run on init.