Also, compare the breakdown of the 2020 race:
https://www.opensecrets.org/2020-presidential-race
Biden’s campaign directly spent over $1B, and over half a bil of outside money (SuperPACs, I assume). Trump “only” managed about $1B combined.
IIRC, money spent directly by the campaign is also worth more; they get preferential ad rates.
Harris has already broken $100M in the first few days. Some of that was pent up donations from donors who wanted Biden out.