Search engine says you are not the only one. Not limited to PureOS. I suggest you likewise search.
Complaining about a missing key is not necessarily a problem. https://git.kernel.org/pub/scm/bluetooth/bluez.git/commit/?id=02e46e9df6b0d897e6ba67dc3ea18e5e9c510e44
I couldn’t tell what version of bluetoothd you have but I expect that in time the patch will come through and the messages about a missing key will disappear. Whether that makes any difference to the actual behavior I don’t know.