I had a heavily modded save in 1.20.12 that I continued to play in 1.21.5 with the same mods updated. I encountered a bug where when I try to harvest a crop on farmland it doesn't produce any drops and the only way to acquire drops is if I break the farmland underneath it. If I don't break the farmland but reload the save after breaking the crops the crops are restored as if I never touched them. It's unique to this specific save. I know it was ill advised playing the save in the new version but I don't like the early game and I had a lot of intentions in it still.
This bug doesn't apply to wild crops. They behave normally.
I tried an update to 1.21.6 and a reinstall to 1.21.5 but it doesn't seem to be resolving this issue. I only found one other forum post with this same issue but it was solved with a reinstall.
I have both the 1.20.12 and 1.21.5 modlists in zip files. I'll post them in google drive links but if you are interested in them in another form please let me know.
https://drive.google.com/file/d/1jDqVgNGoITbH590CUTQuKVxwME_5mAyp/view?usp=sharing - 1.20.12
https://drive.google.com/file/d/1IYbbmI8_mb-Adm_o4UnHziCNK1YSBtN5/view?usp=drive_link - 1.21.5
