On Wednesday, 6 May 2020 23:39:38 UTC+1, Paul wrote:

Not all bulbs use SMPS. Some use capacitor-dropper
as a technique, for which the symptoms could be
different. Capacitor-dropper bulbs might not
"regulate" the light level, like the SMPS ones do.
Capacitor-dropper bulbs, can be damaged by transients
on mains. SMPS are much more resistant to that issue.

Yes, I have a box of dead ones, almost all of the type that has
"filament" structures, made by Osram. I don't buy that sort any
more.
John