question

Forget the % display for a moment. I'd argue its nearly useless for those that don't spend a considerable effort calibrating parameters. Give us a screenshot from the VRM app of the daily charge profile (min/max batt voltage, charge phase duration etc.)
Also, is it a flex or solid panel and how is it mounted?

I recently saw a van-lifer in Italy who had a rail partially shading his panel. Any shading, even a very small bit, will knock a single panel’s production to a fraction of its potential. Make sure nothing on the roof is casting a shadow: wires, racks, luggage, fan covers, etc. Check wiring and connections, as well. Poor or damaged connections waste energy as heat, and can be a fire danger if left unaddressed.

Next you can check the panel voltage to see if it is operating correctly, aside from other components. There are many videos out to show you how. Then test one step further at a time. Ultimately, the batteries may be at a diminished capacity and are charging as high as they will. A step-by-step approach is best to troubleshoot these things. Viewing it as a system can introduce confusing variables.