If you want to be certain you can check your nutrient levels (NPK) to see if they’re spiked which would indicate the presence of ferts.
I would definitely recommend to never leave the wool on a plant if it’s going in your water. Much better to risk killing half roots than putting an absorbant pad of whoevers water into my tank. If you didn’t clean them very well you’ve likely got hitchhikers too.
Gotta be careful. Didn’t mean to be abrasive if that’s how it came off, it’s just worth taking the couple extra mins to do things right.
Its not fertilizers, lots of places grow their aquatic plants using a high copper setup to kill off unwanted pests, like snails, in their production. Unfortunately residual copper from the plants/wool will affect your tank and kill your inverts if you put the plants in directly. Its generally recommended for shrimp tanks to quarantine new plants (Unless its tissue cultured), to avoid this. Usually because shrimp tanks are quite small they are much more affected by residual copper from new plants than a large community tank would be.
Drop new plants in a plastic bucket with some water, then do a water change daily for a few days and you should be good to then add them to the tank (although do always remove wool or other substrate the plants came with).
If you do 50% water changes a few times the next week you should be okay to re-add shrimps to the tank.
surreal-sunrise 
If you want to be certain you can check your nutrient levels (NPK) to see if they’re spiked which would indicate the presence of ferts.
I would definitely recommend to never leave the wool on a plant if it’s going in your water. Much better to risk killing half roots than putting an absorbant pad of whoevers water into my tank. If you didn’t clean them very well you’ve likely got hitchhikers too.
Gotta be careful. Didn’t mean to be abrasive if that’s how it came off, it’s just worth taking the couple extra mins to do things right.
Its not fertilizers, lots of places grow their aquatic plants using a high copper setup to kill off unwanted pests, like snails, in their production. Unfortunately residual copper from the plants/wool will affect your tank and kill your inverts if you put the plants in directly. Its generally recommended for shrimp tanks to quarantine new plants (Unless its tissue cultured), to avoid this. Usually because shrimp tanks are quite small they are much more affected by residual copper from new plants than a large community tank would be.
Drop new plants in a plastic bucket with some water, then do a water change daily for a few days and you should be good to then add them to the tank (although do always remove wool or other substrate the plants came with).
If you do 50% water changes a few times the next week you should be okay to re-add shrimps to the tank.