Gap years are really common in the UK, not so much in the US it seems. My son is going to take one, and we encourage it. He is going to work for the first part, save money and travel, exploring the world a bit.
I think the important thing is to have an specified end to the gap year, so it doesn’t turn into 2 or 3 years… My son is applying this year as a senior and will defer for a year, to enroll at university Fall of 2023. Many universities will allow this, but some will not. Fingers crossed this works out for him because he doesn’t want to be dealing with the stress of applying for college during his gap year.