Poor performance, execution model limitations, lack of static typing (although they seem to be working on that), and general legacy cruft.

Don’t compare PHP to Node, Ruby or Python, they also have problems. I think Go is currently the best choice for a web backend; an objective evaluation of PHP and Go would certainly put Go ahead. If you know PHP, you can pick up Go in a day or two, so I don’t think that’s a great reason to keep using PHP either.

Usage statistics are a highly misleading, software projects take several years to develop and a majority will fail. Looking at current usage tells you the most popular choice from 5 years ago, not today. Over 90% of video games published in the last 5-10 years use Unity or UE4, but these probably aren’t the best choices today.

One example, Chuwi Larkbox X: https://www.aliexpress.com/item/1005005715207156.html

This one is cheaper, but lower spec and no-name: https://www.aliexpress.com/item/1005005234838380.html

You can find Intel N100 mini PCs for 100-200 Euros that have similar performance to a 6th gen i5 but much lower power consumption and better codec support including AV1. The i3-N300 is also starting to become available with twice as many cores.