Keep location sharing intentional
Sharing your location is fine when you choose it. The trouble is forgetting it's on, or letting an app turn it on by default.
Both iPhone and Google Maps support timed shares (1 hour, until end of day). Prefer these over 'indefinite' — sharing ends automatically.
Calendar reminder every 3 months: open Find My / Maps / Snapchat / Life360 and remove anyone you no longer want to share with.
Strong password, 2FA, and review of authorised devices on Apple ID and Google account. If somebody else can sign in as you, they can re-enable sharing.
Family Sharing is useful for parents and dependants, but agree explicitly on what gets shared. Adult children don't need to be in the same group as minors — set up separate ones.