As explained by @onur-ozkan

Just checked the source code, activation and deactivation operations are relying on the CoinsContext Mutex.

e.g.,:

activation requested -> TendermintCoin initialized -> spawning tx/history / balance streaming futures -> locked(no parallel execution allowed here) coins context and added TendermintCoin in there -> success result

However, spawned futures can end up unexpectedly because there is no guarantee that they will be successfully executed/initialized before we add their coin into CoinsContext. This means that a spawned future could encounter errors or panics after we add the coin to the context and return a success result.

ref. #1978 (comment), #1978 (comment), #1978 (comment)