I set up a villager trader. I place the lectern block, and usually break the lectern until I get the right trade. If I leave the area during this process, or log out at any point, the trades remain the same as the last shown trade and the villager no longer swaps trades, even though I haven’t traded with the villager. I tested this on several villagers, and it’s consistent.

also I’m not clear what version this is on, I have a PS4 and am using the latest bedrock version which is 1.17 (and plus some amendments as I have installed all updates that were rolled out)