I'm not sure if this was caused by the last update but I no longer see iron golems spawning. I got 3 iron ingots after clearing up the leftover iron from the chest meaning it still kinda works but it's all that I was able to collect. I'm also not sure but the villagers might be the main cause of the problem since I don't hear them use the fletching tables. I tried removing the worker blocks and placing them back properly but it didnt seem to work
Most likely your village center shifted upwards to a workstation above the lower row of beds, leaving the farm with just a few valid spawning spots on the one side of the raised outer rim of the spawn platform. There are more stable designs for 20-villager farms, but this is an issue where you can get help from the community via Reddit, Discord, or a tutorial video. It’s not a bug.
It’s also possible that the fletchers have switched workstations and can no longer access the ones they are linked too. The is a bug report on workstation switching that explains how it can occur at MCPE-46157. But again, designing around that is something you should get help from the player community on. It’s not the purpose of the bug tracker.