The mod malilib-fabric-1.16.4-0.10.0-dev.21+arne.2 causes Fabric to print the following to the game log.
WARNING! Mod malilib is only using deprecated 'modmenu:api' custom value! This will be removed in 1.18 snapshots, so ask the author of this mod to support the new API.

As it says in the line above, if you want to be able to update to Minecraft 1.18 or above (est. late 2021 or year 2022), you will have to make some extra changes to the mod's metadata.

can confirm, this being in logs is annoying af, especially when you have a bunch of mods that have this

"Annoying AF", really? This also only started happening as of Mod Menu 1.15 or 1.16, I assume they added new things how mods should now define their type as being a library. So I'm sorry if I don't test against all other mods every 5 minutes to check if they changed something that used to work one way and would now work another way just to avoid one warning in the logs.

So I'm sorry if I don't test against all other mods every 5 minutes to check if they changed something that used to work one way and would now work another way just to avoid one warning in the logs.

I wasn't suggesting that you should, I was simply stating that this issue can be annoying when you have many mods. I understand that this isn't your job, that you do this for free, and that you have many mods to work through and a large todo list that keeps getting longer. I'm sorry if my phrasing got you to interpret this as me pushing you to fix this quickly, or something similar, as that wasn't my intention.