Signal itself also has a long dedicated documentation page to help users prevent their phone from throttling it: https://support.signal.org/hc/en-us/articles/36

Signal itself also has a long dedicated documentation page to help users prevent their phone from throttling it: https://support.signal.org/hc/en-us/articles/360007318711-Troubleshooting-Notifications https://support.signal.org/hc/en-us/articles/360007318711-Tr... I presume these manufacturers allowlist WhatsApp by default. Hopefully Signal getting more popular will help it in that department.