Why is prestotex.com not loading text and buttons for some customers?

A customer reached out the site wasn’t loading text or buttons. On my end, I’m not seeing any issues on mobile or desktop but we have had a few customers over the past few months say there are experiencing loading issues. It seems they were on desktop but I’m not sure what browser, it looks like it might be chrome. How can this be fixed to prevent future customer issues? thanks!

website: prestotex.com