Overly long review process (>2 years) without feedback
Perhaps the time for being polite is past.
Ask them for a realistic projection about a decision. Perhaps even mention the impact of the delay on the careers of junior members.
There might be reasons for a long delay, but not for a long time between communications. Don't ask for an immediate decision unless you want to risk the inevitable rejection.
But it is their responsibility to choose reliable reviewers.
But if your paper is especially esoteric, making it hard to find suitable reviewers, then starting over will also lead to long delays. If that happens, keep a tighter rein on the process.