The old A123 ANR26650 M1 specification stated it but I'm having trouble finding a copy of the old datasheet. HKJ copied the info and put it on his website
This site also talks about it
Then there is also a couple on YouTube that put lithium in their RV a decade ago and the distributor was telling them (per manufacturer) to charge up to 3.8 or 3.9VTechnical Information LiFePO4 Care Guide: Looking after your lithium batteries
LiFePO4 Care Guide: Looking after your lithium batteries - Technical Information LiFePO4 Care Guide: Looking after your lithium batterieswww.evworks.com.au
Yes, this is "outdated" information as we now know that there is no benefit above 3.65. That might even change to 3.60 one day
Just because it's old information does not mean it is incorrect. It is the max safe charging voltage. You have nothing to gain and you have no body parts to lose but cycle life is something you will very likely lose.
I had thought this was well known information on this forum.
Cuz this...and then they fail.