The magic of solar and storage does have it's internal gremlins. Didn't realise Time Ampere is a brand of LiFePo4 battery.
The BMS could be doing something strange in there. Not knowing anything about it, if it's constantly trying to balance a bad cell or set of cells it will be draining the healthy ones.
But the main thing I've found after sitting and watching voltage rise from the different types of battery chemistries is Li based systems don't ever like to go near their maximum volts. Pb tech loves it. Ni not as much, Li never from my experience. You can watch the voltage rise on LiFePo4 at the end of it's charge voltage and it will just keep going up without some way of artifically stopping it

. The beauty of Pb tech is the internal resistance will keep rising to match the full battery state.
I've used the major battery types and NiFe and NiMh are my favorite. I keep my homemade 24v LiPo with a close eye on it. 40-80% SoC. Individual cell monitoring with BMS. I tried LiFe but wasn't convinced it would work for me.
I've probably wasted a lot of time watching voltage go up from solar. It is magical.