The comb-like pattern on the text makes me suspect an interlacing issue. There's a mismatch somewhere in the image pipeline regarding whether Resolve/Fusion is expecting interlaced or progressive footage, and whether or not it's actually getting interlaced or progressive footage. It's hard to diagnose without knowing your settings, but look for options related to "fields" and make sure you haven't changed any from their defaults. If your footage actually IS interlaced (unlikely if it's from a camera built in the last 15-ish years), then you would need to change these settings from their defaults.
Assuming progressive footage, in the Resolve Project settings, make sure that under "Master Settings," the "Enable video field Processing" box is unchecked. In all Fusion Nodes, in each "Image" tab, make sure "Process Mode" is set to "Full Frames."
Another possibility is that the viewer is showing you an inaccurate preview. On the Edit page, the viewer takes certain shortcuts to speed playback. Exactly what Resolve does isn't documented, but it's likely to affect scaling, which might cause display artifacts. For a more accurate (but slower) preview, you can disable "Performance Mode" under the "User" tab of the System settings, in the "Playback Settings" category. If your rendered output doesn't display the same artefacts as the edit page, this is likely the culprit. Setting the viewer scale to 100% would also show an un-scaled image. Alternatively, viewing the image on the Color page will prioritize image quality over playback speed.