before then charging north towards warmer air

[Maybo]

For three decades it was a static "ice island". It didn't budge. It wasn't until 2020 that it re-floated and started to drift again, slowly at first, before then charging north towards warmer air and waters.

Source: World's biggest iceberg spins in ocean trap by Jonathan Amos and Erwan Rivault, BBC

I feel like it should be only "then", no before. Or does the sentence mean "before slowly drifted and then charging north"?

 

[Rover_KE]

I feel like it should be only "then", no "before".

I agree with you (or the other way round).

(I expect you're aware that 'charging' is a wild exaggeration of 'moving more quickly'.)

 

[Tarheel]

Icebergs move at the same speed as the current that moves them. If it wasn't moving at all before then moving would be an increase in speed.