I noticed in the game discussion group that some people say that the maximum value of version 1.17.1 cannot exceed 255, so I tried it and found that this problem does exist. At the same time, I asked my friend to try the versions below 1.17.1, such as 1.16.5 and 1.17, and found that they both exceeded level 255. I suspect this is a bug, because the problem reported by MC-172733 is similar to the current one, so I hope to fix this bug as soon as possible.