Here's a complete tutorial on how to downgrade iOS 11.4.1 to iOS 11.4 on iPhone, iPad or iPod touch right now.

Downgrade iOS 11.4.1 to iOS 11.4 Today if You Are Having Issues - Limited Time Only Window

Update: Are you downgrading for the Electra jailbreak? Then follow the guide posted here:How to Downgrade iOS 11.4.1 to iOS 11.4 Beta for Electra Jailbreak

Looking to downgrade iOS 11.4.1 back to iOS 11.4 for any reason? You have a limited time-frame to do so as Apple is still signing iOS 11.4. There's no telling when Apple would stop signing the older firmware therefore make your move quickly if you wish to ditch iOS 11.4.1 completely.

First and foremost, keep in mind that this process will erase everything off your device. Take a complete backup of everything using iTunes or iCloud before going ahead. Also, you will require iTunes (apple.com/itunes), a Lightning cable and the iOS 11.4 firmware file which you can download from here. Once you are done with everything, follow the steps written below:

Connect your device to your computer using a Lightning cable.iTunes should launch automatically once your device is connected. If it hasn't, do so manually.Now click on the tiny little iPhone-like icon on the top left hand side of iTunes.Click on Restore iPhone while holding down the left Shift key (PC) or the left Option key (Mac).Select the iOS 11.4 IPSW file and let iTunes restore your device.Once the device is restored, you will see the Welcome screen on your iPhone or iPad. Set up your device the way you like it to be. You may restore from a backup at this point if you desire.

Given that iOS 11.4.1 is packed with numerous bug fixes, I would recommend sticking around with the latest update for your iPhone and iPad. But if you have a truly legit reason for downgrading, then it's entirely your call. Maybe you are hoping for a jailbreak in the near future, which is understandable, as there is a higher chance that an older version of a particular firmware lineup is likely to get rooted before anything else.

While you are here, you may like to check out:

iOS 11.4.1 is Now Available for Download – Update Today