The issue is they forked sane GPL code (Trezor's), then decided they wanted no one to be able to copy them in turn so they rewrote components and messed up entropy. IIRC they intended to still use the secure element to generate some but it failed open and had no meaningful tests to detect so, leading to significantly fewer bytes for years.

Tests should have caught that, and it should not have simply failed open during the most critical part of entropy generation.