just did a holiday insurance quote for 3 adults 2 kids. £37.50 if I say we’re all healthy.

Now I thought I’d get a quote with my migraine and high cholesterol, and my wifes depression.

New quote for all 5 of us is £19 in total

weird

anyone work in insurance who can explain this?

You’ve probably just removed a large chunk of medical cover for yourselves, including expensive stuff like heart related issues.

Unless you put in those details and it explicitally said you are now covered for them, you need to assume that they are now excluded from the policy.