While in the past, when a fluorescent lamp operated with a glow starter reached EOL, after several cyclic operations, the whole system was shut down (The starter stopped to try to ignite the lamp, and the lamp didn't work at all, probably because of filament breaking), today, when a fluorescent lamp operated with a glow starter reaching EOL, this always followed by an infinite preheating (Welded starter), or by a mains frequency flickering followed by shutting down at the next turning on (Starter contacts remains open and can't move).
Why this is happens?

More tough filaments, so they do not break as easily. This is the result of the desire to prolong lamp life, so eliminate any other failure then the unavoidable emission coat wear.
Other reason might be, then narrower tubes ask for shorter filament shape, what bring the necessity to use coiled-coil shape. But as CC is more thermally isolated, from the same power dissipation and operating temperature it has to be thicker. This modification increase the surface of the filament as well, what mean the emission coat last longer. And it made them mechanically stronger, so less likely to break.
As result they do not break even at the EOL on preheat circuit, as older lamps used to.
So then the starter tries to ignite the lamp, till it spent all it's life and fail - or weld contacts together ("permanent preheat"), or break the weld between lead-wire and the bimetal (open failure after start attempt - usually result of welded starter cooling down).