Two things I’m noticing. First off, it looks like you’re logged into Zwift twice - once from an iPhone and also from a Windows 7 PC. While it’s fine to use multiple devices, logging into both of them at the same time can cause problems, including issues gaining speed as Zwift could be accounting for the lack of power output from your second connected device. Please make sure you’re only logged into Zwift from one device at a time.
Since you’re using Zpower on a classic trainer, it could also be that your speed sensor isn’t mounted accurately or isn’t sensing the magnet pass on each spin of the wheel. You may also be experiencing tire slippage if you’re losing speed. Please check both your speed sensor and your tire contact.