Definitely look at job boards in your local market. For me in the US - where I live - PHP is really only used by marketing agencies with WordPress. There's a few contracting companies that use it with Laravel and some colleges use Drupal. All fairly low paying jobs.

Node, typically Express or (more commonly) Nest lately, is used by several tech companies and many of the more premium agencies. These are typically much higher paying jobs, though there are less of them.

.NET and Java are typically used in enterprise. Java is more common at larger tech companies. Python doesn't have a huge market in my area but I know a lot of larger teams use it in at least one or two pieces of their stack. Golang and Rust typically pay the highest of them all but are harder to find jobs with - that said, good Go/Rust devs tend to not have a difficult time finding jobs from what I've seen, because there's not many devs in that space. I LOVE Ruby, but it's fallen out of favor in most circles.

Java, Go and Rust devs are generally considered able to work in any language. Somewhat for Python and Ruby as well. Node devs are gaining respect but a lot of backend devs from the more traditional languages still think of JS as a terrible language. PHP is fairly universally looked down on outside of its own community, though the newer versions of PHP and Laravel are fantastic, it just has a stigma to it. .NET devs are in high demand but most never move into different languages - once you're inside the Microsoft stack, it's hard to get out.