SOLUTION: the Spray Diverter Assembly needs to be replaced. It’s fairly easy to do.
Peerless faucets have a Lifetime Warranty for the original owner. Call 1-800-438-6673 for free replacement parts sent to you.
If you’re not the original owner or need it fast, see a link below to purchase it. It’s around $15. this product.
In this video, I’ll show you how easy it is to fix bad sprayer flow on Peerless P299568LF, P299575LF, P299578LF. This is when the sprayer is in use but water is still flowing through the spout.
Diverter Assembly part number: RP41700.
If you need it fast or they don’t honor your warranty, you can buy the part here here:
https://amzn.to/2GHeJgu