Dyson Suggested Filter Replacement for V15 Despite Lifetime Guarantee

I sent my V15 device in for warranty service, and alongside other recommended procedures, they suggested that I replace the filter. Why was a replacement merely suggested instead of performed? My understanding was (a) the vacuum was still functional, just not operating at maximum efficiency, and (b) pet hair might be affecting it. However, the filter is marketed as “lifetime” on your website, and the V15 is supposed to handle pet hair with no issues. Why, then, am I being advised to replace the filter rather than simply having it changed under warranty? Are you suggesting that the device is fine as long as it works, even if it lacks full suction power? Or is there an implication of user error based on my initial call with customer service? If so, what is this “user error”? I have followed all instructions to clean the filter after each warning, ensuring it dries completely. Since effective communication with the call center has been challenging, I am raising this as a formal complaint.