Here is what I believe to be the case, experts and more frequent practitioners of BP change can provide more clarity.
Earlier when you changed the BP, the quota for the BP would become applicable instead of the station from which your reservation starts e.g. BDTS to NDLS reservation would use the quota of BRC - NDLS if you changed the BP from BDTS to BRC.
Sometime in the recent past (I dont know exactly when) this has been changed and now the quota of the station from which your reservation starts would...
more... be applicable regardless of which BP you choose. Hence in the same example, the quota for BDTS would apply regardless of what BP you choose.
Are you suggesting that changing the BP to BRC resulted in the quota of BRC being applied to your ticket instead?