> Senior devs are nowhere to be found through regular applicant pipelines. They seem to be leaving as a result of reaching out to friends/former colleagues.

Which makes sense. Everyone learns that the best way to get jobs is skip the recruitment pipeline by using your network.

The recruitment pipeline is so miserable at most companies, why would you put yourself through it unless it is absolutely your dream job? Even then it's probably unnecessarily stressful and time consuming and annoying. Way better to make contacts with people where you want to work and just skip it.