Thanks again – I deactivated all plugins except for ACF and the issue remained. I did notice that the user agent stylesheet contained the following for the ul:
margin-block-start: 1em;
margin-block-end: 1em;
margin-inline-start: 0px;
margin-inline-end: 0px;
padding-inline-start: 40px;
When I added margin-block-end: 0; to the class .acf-fields > .acf-tab-wrap:first-child .acf-tab-group the first field was able to float all the way to the left.
The site is running WP 6.2.2 and the latest version of ACF Pro 6.1.7
