Oh the Biomes You'll Go Refabricated recently added a biomepedia to their mod. The button in the inventory for the book can be turned off in a config, but the mod always gives the book to the player on login and currently StarterItems does not clear it out even with the clearInventory set to true in the config.
I am not using the Forge version of BYG, but I imagine the same is true with that version as well.

StarterItems version: starterkit-fabric_1.19.x-3.1
Minecraft version: 1.18.2 on Fabric
Fabric API: 0.55.1 (though I have also tried it on 0.48.0, 0.51.1, 0.53.3 and 0.53.4)
Oh the Biomes You'll Go version: Any version from 1.18.2-1.4-RC-12 through 1.18.2-1.4.1 ( I have not tested any of the 1.19 versions)

Yes this is a known issue. It's because StarterItems attempts to clear out the inventory when a player logs in, and it already has logic to try to do this after every mod, but some mods use other mechanisms to add items to the player - such as through an achievement or other - so it's not so easy to make sure StarterItems clearInventory is always called AFTER other mods' logic. It has to be done in a more ad-hoc way

I'll have to look into this and see if I can figure out how to make sure clearInventory is triggered after whatever BYG did

Though, I noticed you linked the wrong mod:

StarterItems version: starterkit-fabric_1.19.x-3.1

Did you mean to put this in the starterkit Issues page, or were you having this problem with StarterItems?

Fixed in 1.5.5-1.18.2+ and 2.0.1-1.19+

Though, I noticed you linked the wrong mod:

StarterItems version: starterkit-fabric_1.19.x-3.1

Did you mean to put this in the starterkit Issues page, or were you having this problem with StarterItems?

My apologies! I was testing both mods and was looking at the wrong page when I posted. I meant to post
StarterItems version: starteritems-1.5.4

(edited original post to strikethrough incorrect mod for any future searches)

Thank you so much for the quick reply and update! I downloaded the new file for 18.2 and tested it this morning and it works perfectly. Thank you again!