Low ranking home page compared to rest of site.

My site is decades old now, but recently noticed something I am not sure about… In 2018, my home page ranked for about 400 phrases. Today it is only 3. My overall site has about 2,000 phrases in the top 100 - but it had been around 7,000 in that 2018. I just am curious why my home page would have so few compared to sub-pages. The site has high 90s CWV. It just seems strange and competitor home pages have many more phrases. Any thoughts on what to investigate?