Our 2020 cars handbrake was originally not great, it worked but with little bite. We had a lot of rear brake issues over 12 months, from semi seized calipers to an annoying rattle/knock in their area. Many things were checked and one disk replaced. In the end the complete set of rear calipers and their mountings were replaced.. This completely fixed eveything. The dealer did say that when they compared the original calipers with the replacements the originals seemed to be not so well made??.
I have also noted that the caliper brake arms are at slightly different positions when the handbrake is on, now considering that both calipers are new(ish) and the disks are not worn I would expect the arms to be at the same position, I can only assume that there is a semi auto adjustment system in the handbrake mechanism in each caliper, as the handbrake operation is integral to the unit. I have looked for a Eng drawing of the caliper to try and work out its handbrake operation and how ( if possible ) to adjust and de adjust it , but so far no luck.
