ypercubeᵀᴹ: Both transactions want to delete the row with name = 'lg4xdzvn2bth' and age=99. Tran 2 was second to request that so it was waiting. But now Tran 1 wants to delete all the rows with name = 'lg4xdzvn2bth' as well which tran 2 has already locks on. So they are both waiting on each other locks. Deadlock.

ypercubeᵀᴹ: When you delete a row you need to delete the reference to the row in all secondary indexes. Both transactions want to delete the row with name = 'lg4xdzvn2bth' and age=99. 

Tran 2 was second to request that so it was waiting. But now Tran 1 wants to delete all the rows with name = 'lg4xdzvn2bth' as well, which tran 2 has already locks on. 

So they are both waiting on each other locks. Deadlock.