RAID6 vs RAID10+LVM why does 10t behave inadequately after the load on the disks is more than 50% (LA by iowait limits to 100%)?

Question

Hard disks

Top graph LA, bottom iostat rate(io_time_seconds_total) (device utilization)
RAID6 on the left, RAID10 on the right
When the utilization of each of the disks exceeds 50%, the utilization of the device mapper tends to 100%. As a result, LA rises to 100%.
Is LVM to blame. With what it can be connected? Whether it is possible to solve this problem somehow (somehow LVM for example)?
At what the first stripe from RAID10 is loaded at peak loads by 10-15% more than the second one
Thanks