Their maximum length is inconsistent with what the actual client supports and what is stated on the documentation of the API.

As the documentation states, the maximum length for both of them is of 16 characters. But implementations as far back as 1.7.10 (as far as I checked) have always allowed up to 32 characters. That allows plugins to create prefixes/suffixes too long for the client, which disconnects from the server upon receiving.

https://hub.spigotmc.org/stash/projects/SPIGOT/repos/craftbukkit/browse/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftTeam.java#53

https://hub.spigotmc.org/stash/projects/SPIGOT/repos/craftbukkit/browse/src/main/java/org/bukkit/craftbukkit/scoreboard/CraftTeam.java#67