If you don't clean up your browser cookies and settings between your VPN sessions and sessions where you're not using the VPN, you're effectively negating the privacy provided by the VPN.

I thought my favorite browser blocked trackers but this free privacy tool proved me wrong ...

Because of this, it's good to clear out your cache every so often. It allows you to remove data you don't need on your phone, especially if an unknown data tracker is among your phone's cookies.