I complain here and everywhere about the insane complexity in modern-day web app dev.
The truth is that, after you learn the 20 new tools/technologies you'll need to become semi-competent in only one stack, it won't seem like such a massive shift anymore.
I think competition is not that fierce -- honestly speaking as I can -- but that's for corporate jobs, etc.
And you _have_ to be competent or good or really good if you're older.
Else, you're just going to sound...like you sound -- old and washed up.
Not saying you are, or I am, but once you're 25+, if you bring the 'Get off my lawn' vibe, your 27-yo manager-to-be is gonna smell it a mile away, and he's gonna be feeling awkward enough already.
So I think you can be fine, but you gotta actually know what you're doing, and you have to get/be modern.
A LOT of companies change the whole stack just to copy the latest gimmick they’ve seen somewhere else.
Devs need to be constantly relearning how to do basic things, so you either chose some tech and hope it gets popular, or you get to know a lot of frameworks only superficially, which leaves a lot of the internet broken.
Anyway, C# is still very relevant, but it depends on location. In my city, it's huge, in others, not so much. I tend to stick to back end work rather than front end work. Front end's flavor of the day changes way too often, and I find it to be tedious work. Back end is much less reliant on external libraries and therefore doesn't change as rapidly, and to me is much closer to actual programming.
So in summary, talk to your prior colleagues, stick to back end work (if that's your bag). Keep on truckin'
About your skills, There are many new trends in tech in last decade. Since you have worked withe web, I will suggest you to start with HTML5, CSS3 and Javascript's new features which you may already be knowing.
Start learning server side js. Node.js is bit confusing if you are old folks but see some tutorials and follow them, start with light framework like Express and make small app. The benefit of node.js is you can share many modules at both server and client sides if needed[though beware of it].
Alternatively if you want to stick to PHP, the easiest will be to start with codeigniter and when you feel likes getting grip move to Laravel. Laravel is in great demand. Learn to use it with docker.
Building successful solutions and helping to evolve a business is inherently more valuable skill to the guy who signs a checks.
If he is smart enough he is less care about technology you know at this given moment but more about you passion, inspiration and ability to help the business grow and learn new fad along the way if needed.
If you're facing overzealous interviewers nitpicking your coding skills or short cycled in forcing you to solve stupid puzzles in record short time - it is likely there is a disconnect within this organization on what is really important and you'll be wasting your valuable time agreeing to work there.
[1]https://starecat.com/the-technical-interview-vs-the-actual-j...
Your skills are very relevant at least with WP. Are you not looking for WP jobs ?
Do not doubt yourself based on your interview performance. If it’s something you care about and you have the time, do your test prep properly: big O, tree traversals, etc. etc. etc.
I’ll add that as a primarily functional programmer who’s applied for multi-paradigm jobs, I’d say a lot of the answers I’ve been expected to give were quite absurd.
Algorithms is one way of achieving this goal (another question if it’s good way).
Since CSS knowledge (and honestly wordpress) is not a big deal (you don’t have to be smart to learn them) — make sense that interviewers asking you a lot of stuff.
Can you complete projects of at a minimum, small size?
Then, yes.