Promptweet does not set server cookies. What it does use is your browser's local storage, which behaves like a cookie in spirit: small values saved on your device, read back on your next visit.
Necessary: routing and layout state while you use the site. Always on, since the interface needs it to function.
Preferences: your theme (light/dark), bookmarks and cookie choices, remembered for your next visit.
Analytics: not currently in use. The toggle exists in settings for when it is, but nothing is tracked yet.
Adjust what is remembered at any time on the Cookie settings page, or clear your browser's site data to reset everything at once.