Blurry text after render and export

Never scale text from Motion, this will reduce text quality.

Always use scale properties from Vector or Text to adjust text scale and preserve text quality.

Concerning Legacy text, scale it from within the legacy text window and not from Motion.

If the issue persists, check your renderer from project settings and try to switch renderers.

If you only have software only available, then consider updating your gfx card from the vendor's site.