As explained in https://www.curseforge.com/minecraft/mc-mods/spawn-balance-utility, please consider balancing your mob spawns in lower values, so they play better with other mods' spawns and vanilla spawns.

As it stands right now, dragonflies, sea bunnies, koi fish, otters, and leaf insects are so outrageously spawn heavy that they drown out all other mobs, and it's getting to the point where I've removed this mod from our server until the weights have been fixed. Not that one person matters, but I can't imagine all other server owners aren't seeing the same drastic imbalances in their spawn ratios.

Thanks for reporting the issue.
This is weird. The current spawn weights have been tested and never presented any problems, in fact, there are people who still find it difficult to find the mobs you mentioned.

We would appreciate if you could provide more information about your environment in this issue (Minecraft version, mod loader, installed mods, etc.).

Here's a gist of all the mods that load on the server side.
Minecraft 1.19.2 with Fabric Loader 0.14.21
https://gist.github.com/purejosh/f5675ed32e738d9a4066e352442f7839

To narrow it down, the mobs that have severe overspawning are mobs like dragonflies, sea bunnies, and leaf insects. Koi fish are less of an issue, after they were assigned to the ambient water group in the last update, and otters are plentiful but I wouldn't consider them the biggest offender.

For transparency, I have not looked into these spawn weights myself. It's just an observation from my server players that these mobs are spawning too often.