Flame graph structure might be broken in certain cases:

I was able to reproduce the issue only with Go heap alloc_* profile types (heap inuse_* are fine). My understanding is that it might be caused by the fact that these are cumulative profiles.

On the other hand, the exported pprof is valid and does not appear to be malformed. Importing it via ad-hoc profiles results in a valid flame graph. My theory is that the data gets corrupted either during its journey from the data blocks to the query frontend, or while converting the tree to a flame graph.

Might be related:

• Malformed flame graph when importing delta heap profile from Go #3616
• Investigate negative sample values #2285