Hello Phoenixrizes,
Welcome to Apple Support Communities! I understand you're having issues sending gifs while on
Wi-Fi. I'm happy to assist you with this.
Let's make sure you have our latest iOS13.2 update: Update your iPhone, iPad, or iPod touch
Next, let's check some settings.
1. Test sending a gif message as per the info in this hep article: Send and save GIFs on your iPhone, iPad, or iPod touch - Apple Support
2. If it is not working, try turning Wi-Fi off and be connected to your cellular connection. Please be aware this will use your cellular data until you re-enable Wi-Fi in Settings > Wi-Fi. Connect to Wi-Fi on your iPhone, iPad, or iPod touch - Apple Support
3. If it works while connected to a wireless network, but not cellular, check Settings > Cellular. Ensure everything is enabled you want to be able to use while you are not connected to a wireless network. Depending where you are getting the gif image from, you may see an option for "HashtagImages". Ensure that is enabled. Check the cellular data usage on your iPhone and iPad - Apple Support
4. If this is not working with non-iMessage messages, please check Settings > Messages. Make sure "Send as SMS" & "MMS Messaging" are both enabled. About iMessage and SMS/MMS - Apple Support
Test again using the article in step 1. If this has not resolved your issue, please provide more info about when it occurs, what you are seeing when it fails, and any alerts or error messages you receive. Thanks and have a wonderful day.
Best Regards.