Best known invalid block, tracked to detect a longer invalid chain than the valid one.
Declared in <validation.h>
[[guarded_by(0x7ff37ba944a8), guarded_by(0x7ff375ddae38), guarded_by(0x7ff37e1a4708), guarded_by(0x7ff375a96578)]]
CBlockIndex* m_best_invalid = {nullptr};