Hmm. Now this is interesting. As far as i knew Sylvania only used bakelite endcaps on their REALLY old tubes. This looks like an 80s or very early 90s tube though. I have a 30-pack case of Sylvania F20/WW lamps from 1985 that have this etch but have the old 60s and 70s lifeline endcaps. That's why i got them (the case was opened for display purposes as it was at a fleamarket type place but all the lamps were in and all original and NOS) I didn't think to look at the etches before i bought them but i still don't mind that they're not lifelines. it's the same lamp just a different etch. I knew they were warm white when i got them but yeesh i didn't know how yucky and pink halophosphate /WW lamps are lol.

Sounds like "to use up" lamps for sure then. But same here, I saved some warm white GE mainlighters (multiple cases actually) since they're vintage, even though I dislike the color. I use some though randomly here and there when I need a lamp, until I can't stand the color any longer.