Disk Tier High RAID 10-2 has substituted page allocations with different Disk Tier and/or RAID Level

Hello!

We have storage system Dell Model: CT-SCv3020.

And we see the following warning:

Disk Tier High RAID 10-2 has substituted page allocations with different Disk Tier and/or RAID Level

Could you tell me what this means and where to look to solve this alert?

Thanks.