Bridge pricing has changed. Previously, a bridge that would cost 3 now only costs 2. This was to correct a bug demonstrated by Drawing Dead's YouTube channel.
Bridges had been priced based on the number of tiles the bridge touched. Now they are priced by the number of steps, which is one less than the number of tiles. Previously, having one bridge unit left over was essentially useless, as the minimum cost for any bridge was 2. Now, the minimum cost for a bridge is 1.
This pricing change also solves a bug where bridges disappeared, never to be seen again. When a player tried to build a bridge but only had one bridge unit remaining in their inventory that single bridge was permanently discarded. If you ever had the feeling that you had lost bridge tiles, this was probably the reason.