GoPro’s newest HERO (2018) action camera was reported to be identical to the HERO 5 but with a downgraded firmware according to a post by Hypoxic.

The GoPro HERO 2018 features a 10MP lens and 1440p 60fps or 1080p 60 fps video recording resolution. The HERO 5, on the other hand, has a 12MP camera lens with 4K video recording capabilities. According to the report, the HERO (2018) can perform just like the HERO 5 by loading it with the latter’s firmware and some modifications.

Hypoxic cannot upload a patch for other people to use due to legal matters but rather posted details on how it was done. Click on the source link below for more info.
Source: Hypoxic
Via: PetaPixel

Have you firmware GoPro Hero 2018?
I have Hero2018, i upgrade to HERO5 but I need came back to old/original firmware GoProHero 2018. Can you help me?
Why you need to have the Hero 2018 firmware? Is there any problem on your GoPro after the Hero5 firmware version update?