In Java version 21w37a for 1.18 over a year ago, the 16-character limit for scoreboard objectives was removed. Source: https://www.minecraft.net/en-us/article/minecraft-snapshot-21w37a

This change has not been ported to bedrock edition.

How to reproduce

/scoreboard objectives add reasonably_long_name dummy

Expected result
It works
Actual result
Error message