@faizalialiali Reduce images size using cloudconvert or any other tool. Use any shopify plugin that can help you minify css files like Minify Me. That's the process, that helped me improving the core web vitals of my website.

Do your site audit and check if site is getting any backlinks from spammy websites. Compile those domains and make a list and add them in google disavow tool. That is what i do, for my clients and my own website.

@Halmblogmusic Use google disavow tool to get rid of spammy links.

@Skites2 make a list of spammy domain and add them to google disavow tool. simple.

you can check domain age by using whois domaintools

There are multiple to tool for seo audit but my personal favorite is screamingfrog.