Looks good so far. According to zabbix my server wrote 865 GiB/day averaged over the last 3 months to the 5 disk raidz1 pool.
I moved 3 of the 24 VMs/LXCs to that newly added LVMthin disk and now it averages around 420 GiB/day for the raidz1 + 81 GiB/day for the LVMthin. So the 3 moved VMs are now only writing 81 instead of 445 GiB per day. 81 GiB per day just to store logs and metrics of a homelab is still way too much but way better than 445 GiB.
I moved 3 of the 24 VMs/LXCs to that newly added LVMthin disk and now it averages around 420 GiB/day for the raidz1 + 81 GiB/day for the LVMthin. So the 3 moved VMs are now only writing 81 instead of 445 GiB per day. 81 GiB per day just to store logs and metrics of a homelab is still way too much but way better than 445 GiB.