With 5 x G9 replace one with a tungsten or larger version it also stopped the problems with the other LED lamps, I would assume some reaction with the electronic switch, which allows us to switch bedroom lights on/off in bed with a remote control, I would assume with hard wired two way lighting the problem would not be there.
My daughter has a problem with living room lights, it does not affect us, but we can't really test bulbs, there is nothing on the bulb to say if pulse width modulated driver, resistor driver, or capacitor driver, if there is a smoothing capacitor or not, and how much leakage in each bulb to stop flashing when off.
Although I am using electronic switches without neutrals (Energenie) the way we run the supply to switch and back results in some capacitive and/or inductive leaking, which increases with two way switching, bulbs must state if not suitable for dimming, but that is all they need to do.
So it is simply pot luck, I have a draw full of bulbs where my selection has been wrong, be it output, or flashing, or shimmer, or swapping to some smart bulb, in the old days of tungsten this stock would soon diminish, but since going LED I think two bulbs/tubes have failed, as to if low failure rate is due to having SPD fitted don't know, son seems to have had far more failures which he blames on cheap bulbs.
It may be correct, failure rate may be due to cheap bulbs, but the two which failed with me, the replacement for a fluorescent tube was not cheap, although that was in the house he now has, with no SPD, and the colour changing smart bulb (GU10) also not cheap.
In fact it was the cheap G9 which cured my shimmer problem, OK one did stop working within a day, which I opened to see what was inside, found dry joints, re-soldered and put back in service, which is why I know it has a large smoothing capacitor inside.
Energenie publish a chart saying what make and size of bulbs have been tested and which had no sign of shimmer, or flashing, however my own experience does not match.
I have also had smart switches and sockets fail, and have moved to smart bulbs and plug in adaptors as easier to correct when they fail, main reason for smart devices is fibre board flooring meaning adding extra lights and hard wired switches is not easy, so lights are timed to switch on/off and power failure is protected against using rechargeable torches which light rather than emergency lights fitted to last house.
My days of lifting floors or making holes in ceilings to tread cables are over, unless no other option, yes the hard wired is better in most cases, but often no option, my son with his last house had a server in the loft and LAN points everywhere including one at each radiator point to work the TRV, however you simply can't buy hard wire TRV heads, they are either wifi or bluetooth, so we have no option, can't hard wire even if we want to.
It seems all through my life technology has changed making hard wired devices redundant. I had coax to all rooms from a central spliter/booster with DC through to power the digi eyes so I could change program on the sky box from any room, this was OK with 14 inch TV, today with 28 inch being around the smallest coax not good enough, and sky Q no longer uses digi eyes.
The same applies to telephone and fax machines, again all hard wired, now all redundant, have not used fax or slow scan TV for years. And as to telex, which was considered as legal document, which fax and email are not.
Laws and rules can't keep up, there is a law on outside lights maximum wattage without planning permission of 150 watt, however as far as I am aware never updated to lumen. It would be some where around 2000 to 2500 lumen, but seems law never updated. So LED for outdoors should be around 20 watt maximum, but there is no such limit.
Regulations, laws and rules are not keeping up with technology.