Hi!
There have been other users who have encountered similar problems with Wi-Fi speed on iPhone 14 Pro. Some users solved the problem by resetting network settings or disabling Wi-Fi network services. To reset network settings go to Settings > General > Reset > Reset network settings. Enter your passcode if required and confirm that the network settings are restored. Keep in mind that this will erase all your saved network settings, including Wi-Fi access data and passwords, but you can log back in. To turn off Wi-Fi network services on your iPhone 14 Pro, go to Settings > Privacy > Location Services > System Services and turn off the Wi-Fi Network option. This will prevent your iPhone from using nearby Wi-Fi networks to improve location accuracy.
Also, you might want to check if your iPhone is using a 2.4 GHz or 5 GHz Wi-Fi connection and try changing the connection to see if it improves speed. To check if your iPhone is using 2.4 GHz or 5 GHz Wi-Fi, go to Settings > Wi-Fi and tap the information icon (i) next to the name of the Wi-Fi network you’re connected to. On the next screen, look for the Frequency Band entry. If you don’t see this entry, it means your iPhone is using the 2.4 GHz Wi-Fi connection. If you see this entry and it indicates 5 GHz, it means that your iPhone is using the 5 GHz Wi-Fi connection. If your iPhone is using the 2.4 GHz Wi-Fi connection and you want to try switching to the 5 GHz connection to see if this improves speed, you should first check if your router supports the 5 GHz connection. If your router supports 5 GHz connection, you may need to set up a separate Wi-Fi network for 5 GHz connection and then connect to that network from your iPhone. Check your router’s manual or contact the manufacturer for more information on setting up a 5 GHz Wi-Fi network.
If the problem persists, I recommend that you contact Apple Support.
I hope I helped you!