The website was built by a developer through a mix of 3 programming languages and the blog was built under WordPress platform.
The challenge is that Google makes every month small changes to its algorithm, and every year 1-2 fundamental changes. What was a few years ago an important ranking factor nowadays it may be of insignificant importance…
Platforms like WordPress, Shopify etc have hundreds of developers which work constantly on the code to update it and adapt it to Google’s updates.
But, it is very difficult for a small business which has a website built with codes to keep up and ask all the time the developer to do the updates. At some point the code will become obsolete no matter what