Thank you for your reply.
It's a ZenBook 14 Q407IQ
It was plugged in when I enabled the battery saving mode.
It's now up to 63%.
Oh, when I first noticed it at 61%, I unplugged it and used battery power until it got down to 20% and then I plugged it in and it charged to 60%. It remained at 60% for a long time, to the next day but then I noticed it went up to 61%. It was plugged. It then went up to 62% and just now it's at 63%.
At some point I'll unplug it again and use the battery until it's low and plug it in again but I doubt that the maximum lifespan will stop and keep the battery at 60%.
I'm sure it will stop at 60%, for a good time, like a day or so but based on recent history it will slowly go up again.
Part of me wants to keep it plugged in to see if it will go to 64%, 65% etc. but that kind of defeats the maximum lifespan mode which is supposed to keep the battery at 60% of course (it's just not though).