@Smellyglove good question. The chip has an internal DC-DC converter so I think will most likely result in the same tx power until depleted. However, when the battery is almost dead there will be much instability and packet losses.
@stenr The bluetooth connection has been transfered to the new phone but cannot be activated. Message: An app is required touse this connection. The Flic app is installed....
For other folks finding this as yet unanswered question via a search: FWIW, I have been using magnets on the back of multiple flics for over 6 months now with absolutely no ill effects.