According to the iOS 14 release notes, Apple has temporarily disabled 3D Touch in iOS 14 beta 3. This does not affect Haptic Touch-only devices.
Apple has Temporarily Disabled 3D Touch in iOS 14 Beta 3 - iPhone X, iPhone 8, iPhone 7 and iPhone 6s Users, Don’t Penic
Apple released the third beta of iOS 14 and iPadOS 14 just a while back. And since this is beta software, therefore some weird and wonderful quirks are to be expected. One of them is the unavailability of 3D Touch on devices that support it, which is anything released before the iPhone 11.
Before you completely panic, please note that the feature has been disabled just temporarily. It will be enabled once again in beta 4 or some other release of the software whenever it becomes available.
Apart from the above little nugget, you can expect the overall beta experience to be far better than the second release. Performance should be better across the board, but not perfect, obviously.
You can learn more about iOS 14 and iPadOS 14 by checking out the links below:
iOS 14 Announced With New Home screen, Widgets, and Improved SiriPadOS 14 Announced With New Design Language, Siri Improvements, Home Screen Widgets & More
Looking to download and install the beta instead? We have everything under one roof:
Download iOS 14 / iPadOS 14 Beta Over the Air Without Losing Your Files or SettingsHow to Clean Install iOS 14 / iPadOS 14 Beta on iPhone and iPadHow to Downgrade iOS 14 / iPadOS 14 Beta to iOS 13 [Tutorial]Apple Releases iOS 14 and iPadOS 14 Public Beta - Here's How to DownloadDownload iOS 14 Beta 3 Without Developer Account for FreeDownload iOS 14 Beta, iPadOS 14 Beta for iPhone and iPad