Hi @silver welcome to the /e/ forum.
I had the error once
Error opening camera. Camera maybe in use from another application ID:0
The problem was indeed another app when uninstalled the issue went away. So maybe first check your own installed apps which have Camera permission. (Perhaps Maps might be glitchy if Camera is allowed full time, idk). Edit, or even a bar code reader.
For an alternative camera I quite liked GrapheneOS Camera Option - Possible foundation for a native /e/OS Camera and Simple camera from www.simplemobiletools.com.