As a person in that very job, I can tell you that general use of PHP hasn't changed that much. Assuming you used MySQL it hasn't changed at all as per Oracle's MO.

For the frontend, quite a lot has changed:

• JavaScript ES6 has been out long enough now for it to be the standard - it basically introduces a bunch of useful new features.
• HTML5 has been officially released, which simplifies some tags (e.g. no need to specify the type attribute on script tags), and adds a whole lot more (some functional, some that just grant extra context to your code. e.g. you would wrap your navigation menu in a <nav> tag rather than a <div> tag)
• CSS is where the largest changes have occured in my opinion. CSS3 became the standard many years ago adding many many new features, and additional developments have been made since that have, in my opinion, been out long enough to justify using them in production code. The two most notable in my mind are flexbox and CSS grids. The pair of those have made my job a lot easier
• In addition to the above, the way of writing CSS has changed in many workplaces. I haven't written native CSS in a number of years now; I've instead been working with a language called SCSS (Sassy CSS) - there are alternatives like SASS or LESS. Basically these languages allow you to write logic to generate CSS for you. They can greatly cut down on repetition in the code you write.
• Finally, mobile development has become MUCH more important. Steps have to be taken to minimise your bandwidth consumption (minifying your CSS / JavaScript. Serving smaller images for smaller device sizes, etc), and of course adjusting the layout of your website on smaller devices through the use of media queries.

As a person in that very job, I can tell you that general use of PHP hasn't changed that much. Assuming you used MySQL it hasn't changed at all as per Oracle's MO (However the codebase has been forked a few times e.g. MariaDB, adding a bunch of new features).

For the frontend, quite a lot has changed:

• JavaScript ES6 has been out long enough now for it to be the standard - it basically introduces a bunch of useful new features.
• HTML5 has been officially released, which simplifies some tags (e.g. no need to specify the type attribute on script tags), and adds a whole lot more (some functional, some that just grant extra context to your code. e.g. you would wrap your navigation menu in a <nav> tag rather than a <div> tag)
• CSS is where the largest changes have occured in my opinion. CSS3 became the standard many years ago adding many many new features, and additional developments have been made since that have, in my opinion, been out long enough to justify using them in production code. The two most notable in my mind are flexbox and CSS grids. The pair of those have made my job a lot easier
• In addition to the above, the way of writing CSS has changed in many workplaces. I haven't written native CSS in a number of years now; I've instead been working with a language called SCSS (Sassy CSS) - there are alternatives like SASS or LESS. Basically these languages allow you to write logic to generate CSS for you. They can greatly cut down on repetition in the code you write.
• Finally, mobile development has become MUCH more important. Steps have to be taken to minimise your bandwidth consumption (minifying your CSS / JavaScript. Serving smaller images for smaller device sizes, etc), and of course adjusting the layout of your website on smaller devices through the use of media queries.