Here it should reset growth time if it has no drops
https://github.com/Darkhax-Minecraft/BotanyPots/blob/1.16.5/src/main/java/net/darkhax/botanypots/block/tileentity/TileEntityBotanyPot.java#L327

Also due to the drops are not cached, but the pot generates new drops each time it attempts to harvest. You can simple exploit high value drops by filtering the target container

For example, I have a crop to produce 100% chance for 1 stone and 1% for 1 diamond. I can put place a chest under the pot, and fill the slots with 1x diamond. So if the result has no diamond, it fails to harvest, and try to generate drops next tick, until its result has diamond.

These issues should now be fixed.