The monarch also vets laws while they're being drafted and can make suggestions for changes if they affect their interests.
https://www.theguardian.com/uk-news/2021/feb/08/royals-vette...
The Queen isn't just the head of the armed forces - they swear an oath of loyalty directly to the Monarch, not to the people or the country as a whole - she's also one of the richest people in the world, running an organisation with centuries of experience in internal diplomacy, impression management, and PR.
So it's a complete myth that the monarchy is apolitical. The monarchy is the centre around which the (antiquated) British political system revolves.