This navigation pattern represents sub-sections in the bottom nav bar. This approach proven to be pretty useful in a couple of my past projects so I decided to share.
Two of its main advantages are accessibility and convention. Amongst the disadvantages I'd point out the less defined priority hierarchy of the nav (users have 5 equally visual choices to make with the bottom nav vs something more custom like say Uber).
This post is a part of the ongoing project, "Interaction Library" where I post interesting and engaging human-machine interactions. All posts are tested for accessibility on a real device and are proven to be possible to build. My team and I are always up to a challenge so feel free to reach out for any design and/or development work.
Hit "L" on your keyboard to support this series of UI exploration work. Cheers!