The green bar was almost complete and the fishing rod break it, I'm nor sure if it is a bug or that way work the tool
Your tool is enchanted, but it looks like you have unbreaking on your tool, so the durability decreases slower than usual. Normally, if you don't have unbreaking (or mending if available, but that's not an enchantment obtainable via enchant NPC), you would get that notification when your tool has a couple uses left.
Could you try to count how many times you use a new tool with unbreaking on it and compare that with completely using up a regular tool? The durability should be much different, and if both bring up that warning message when both have the same uses on it, then you've definitely found a bug.