The ratio has always been that of getting 1 sMerit in your balance for every 2 earned Merits. That is the same for everyone, but additionally Merits Sources get an extra monthly supply (different sMerit inner counter, but sMerit just the same).

When the system kicked-off, you had some onetime airdropped sMerits in your account, based on your rank and activity over the prior year. In your case, that allowed you to send more than you received over the first few months, and may have led to the 1:1 perception somehow.

See: https://public.tableau.com/shared/565356JPQ?:display_count=y&:origin=viz_share_link