you need to scale up your compactors to manage the blocklist, without compaction blocklist will keep increasing.
if you increase ingestion, it will create more blocks, and to catch up with that you need to compact. at one point a block reaches the max block size and then it’s not compacted further.
tempodb_compaction_outstanding_blocks is a measure of compaction load, so if it’s not coming down and keeps growing that means that you are not compacting fast enough.
tempodb_blocklist_length is a measure you how many blocks you have in the backend, if your ingestion of retention is increased, it will increase but if your compaction is doing the job, it should come down as you compact more blocks.
If you not on a recent version, please try to upgrade, and also setup monitoring if you haven’t yet.