Best known invalid block, tracked to detect a longer invalid chain than the valid one.
Declared in <validation.h>
[[guarded_by(0x7f2e1bc169b8), guarded_by(0x7f2e146b4d08), guarded_by(0x7f2e298fa0d8), guarded_by(0x7f2e360b7838)]]
CBlockIndex* m_best_invalid = {nullptr};