Please provide the info requested in posting guidelines, i.e plugin environment.
if you backed up your data before updating can you see what plugin style you were using and/or if you had an outdated legacy add-on that allowed you to change your results layout befor or if you had some CSS saved in your WP ooptions table ? I am unaware of any updates to the base SLP plugin that would break or change how the results displayed
https://docs.storelocatorplus.com/blog/appearance-layouts/
There are a multiple styles that work better with some themes. than others, you may want to check them out on your staging or test or dev site.
The Experience add-on allows you to manipulate and change the Layouts and Appearances as well as add CSS if you need to override your theme style.
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