Why does my iPhone 12 Pro suddenly drops off wifi at home, my other devices at home stay on wifi

My phone storage is full

Try to free up iPhone device storage see this Apple articles below:

If you need more space for an update on your iPhone, iPad, or iPod touch

If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

How to check the storage on your iPhone, iPad and iPod touch

How to check the storage on your iPhone, iPad and iPod touch – Apple Support (UK)

Clear Other storage on your iPhone or iPad

Clear Other storage on your iPhone or iPad - Apple Support

What's the difference between device storage and iCloud storage?

What's the difference between device storage and iCloud storage? - Apple Support

Check Wi-Fi connection, See the following Apple articles:

Connect to Wi-Fi on your iPhone, iPad, or iPod touch

Connect to Wi-Fi on your iPhone, iPad, or iPod touch - Apple Support

If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network

If your iPhone, iPad, or iPod touch won't connect to a Wi-Fi network - Apple Support

Recommended settings for Wi-Fi routers and access points

Recommended settings for Wi-Fi routers and access points - Apple Support

If you need help with your Wi‑Fi password

If you need help with your Wi‑Fi password - Apple Support

How to forget a Wi-Fi network on your iPhone, iPad, iPod touch, or Mac

How to forget a Wi-Fi network on your iPhone, iPad, iPod touch, or Mac - Apple Support