Reservation transactions are 1 per 77k, housekeeping is 1 per 70k.
The issue is that, as with the owner in the screenshot I posted, since the August 2021 update their housekeeping credits are being calculated in two chunks instead of a single calculation on their total number of points. So that owner has one resale contract and one developer. One contract is 126k - which on its own only receives 1 HK credit. The other, 256k, gets 3 HK credits. But if you take their total number of points, 382k, they should receive 5 HK credits but they're only receiving 4.
This is because they're treating hybrid non-VIP accounts the same way they treat hybrid VIP accounts. With hybrid VIPs, the calculation works - they have one set of housekeeping credits for their developer points based on their VIP level (either unlimited if grandfathered, or 1 per 70k plus extras based on level if they're a newer VIP), and a second set of housekeeping credits for their resale points based solely on 1 per 70k. When they book, they have to pick which type of points they're using, so the housekeeping credits are never combined. It's two separate sets of benefits. But for a hybrid non-VIP, they don't choose which type of points they're using, everything is already combined, but the system was set up to calculate housekeeping separately on resale and retail points and add them together. I would bet money on my theory that the developers never considered the possibility or tested any scenarios where that two-part calculation could yield the wrong number of housekeeping credits (and sometimes it's correct, just depending on the size of the contracts). It's such a small number of users that they probably didn't bother doing a robust analysis on it when they were developing it, and they have shown no interest in correcting it after the fact. It's easier to say the system is working as intended.