One default font for everything
The logo, headline, body text and buttons all use one plain sans-serif font, often Inter or the system font, usually bold and tightly spaced. It is never wrong, and that is the problem: the type says nothing about the product.
How to fix: Use a font with more character for headlines, such as a serif or a sans-serif with unusual shapes. Keep the plain font for small text. Use two fonts, each with one job.