> because why not?

I'm not certain, but it seems like you're not being entirely serious here, however..

If you aren't joking, or for other people in this position, I'd first wonder if the landing page required a search function that would hypothetically be subject to the vulnerability, then I'd wonder about what the normal nature of your business is and how much latitude you personally have in the allocation of billable hours to arbitrary technology choices and whether those do actually align with the deliverable, then if I was the boss I might wonder why you created a bunch of (potentially) out-of-scope random liability using unusual lesser-known tools based on a personal vendetta against WordPress.

I've been in this position, conceptually if not literally, and I've probably been (in a way, rightfully) fired for it, but my country's labor protections are likely not quite as good as Denmark's.

If there's a question about why money was spent on implementing a bunch of stuff nobody knows for a reason nobody cares about, especially for a very short-lived thing like a landing page, then it's a sticky situation if the answer is basically novelty. Something like this, if it does serve a purpose, should be planned for and a case made for it, but that also doesn't really seem like agency work.

If I was asked for WordPress, which I have, and I delivered Rust, I don't think I'd keep that job, but mileage may vary.

Most work is about solving problems as they are, not what we wish them to be, and if a 5 min job becomes a month long job that the customer didn't ask for, it's an extreme case of yak-shaving.