sum of all mempool tx's fees (NOT modified fee)
Declared in <txmempool.h>
[[guarded_by(0x7fbc8f682898), guarded_by(0x7fbc95d445f8), guarded_by(0x7fbca708a2b8), guarded_by(0x7fbc86272b58), guarded_by(0x7fbca7897238), guarded_by(0x7fbc84ab8888), guarded_by(0x7fbc870f7d88), guarded_by(0x7fbc921df648)]]
CAmount m_total_fee = {0};