Google Pageinsight LCP issue only on mobile device (Vuejs)

After a lot of optimization, I manage to achieve good performance (above 60) on mobile device for my vuejs website, but it does not improve my Largest Contentful Paint (LCP). it remains unchanged.

need some help so I can improve my LCP. Thank you in advance

Visiting https://propertyscout.io/ for mobile on lab data LCP is 3.3 so field data will be less than that from my experience. Following change can help you to improve further on LCP

1. Preload Key since CSS requests are loading from different domain
2. Remove unused JS and CSS.
3. Also load Below fold css in defer mode.