[Solved]-Highcharter deprecated function's output is different than suggested-Highcharts

The graph you want is of type 'stock' instead of the default 'chart' (think 'Highcharts' vs 'Highstock').

Specifying the type solve your issue:

highchart(type = 'stock') %>% 
    hc_add_series(t) %>% 
    hc_xAxis(type = 'datetime')