If you go above lvl 5 you are unable to catch fishes.
Once the bobber hits water, the wait time is determined, and the player must wait for a random period between 5 and 30 seconds (100 to 600 ticks at 20 ticks per second) before the hook catches something.
Each level of Lure enchantment on the fishing rod subtracts 5 seconds from both the minimum and maximum wait time. If it causes the wait time to be less than 0, a new wait time is generated in the next tick.
If you go above lvl 5 you are unable to catch fishes.
Source: https://minecraft.fandom.com/wiki/Fishing
I think after Lure 6 you always get a number below or equals to 0, so it trys to get a new number infinitly. Not sure tho.
85 #87