Special Fishing Modpack! Eternia SMP [Ep.134] - Minecraft 1.20! 

Would also recommend a fishing hut at one of the deep ocean biomes... and staying up all night fishing there. 8-)

For what it's worth, you could totally have used my fishing pole, but unfortunately I tend to throw CoV rods and bows back. I'll try to do better about hanging onto them for just such uses. I think some of the changes made to nerf AFK fishing farms might be affecting your fishing. It's possible the datapack overrides that, but IDK. Those conditions are that, in order to potentially fish up anything considered "treasure," the bobber must have at least two blocks of water to the NESW and below it and two blocks of air above. That could be why the axlotl area seems to have been the most lucrative, since it's deeper and larger than the other two areas you showed.