I have searched for existing threads about this feature request
on
App version
3.13.0-beta1
Problem you may be having, or feature you want
Please 
Don’t remove side navigation entirely.
I understand that maintaining two navigation styles creates extra work, especially for a small volunteer team. But for those of us who prefer the side navigation, losing that option is a significant downgrade.
Suggested solution
Could you at least consider keeping it as an alternative, or create a community poll to see how many users actually prefer side navigation over bottom navigation before removing it permanently?