there was a fairly recent event where a signal conversation between two journalists was compromised. It was done by US intel. (illegally). Evidence indicates they did it through keystrokes before the message was sent. So no, there is no evidence Signal itself is compromised, but there is evidence smartphones are.

Since all traffic at Signal runs over the clouds of Amazon, Google, Microsoft & Cloudflare.

All US services can pick up your meta data directly from there, thanks to the CloudACT:

https://en.wikipedia.org/wiki/CLOUD_Act