Popular documentation like “Mastering Bitcoin” suggests the usage of bx seed for wallet generation.

Secure cryptography requires a source of large, non-guessable numbers. If the random number generator is weak, the resulting cryptographic usage is almost always compromised.

For technical people: in this case, practical wallet security is reduced from 128 bit, 192 bit or 256 bit to a mere 32 bit of unknown key information.

I am not an expert, but if you use a multi-coin wallet that includes Monero, then your Monero could be affected. I don't see a list of wallet software that is affected. It would not be easy to verify that closed-source wallets do not use the exploitable code library.

Q: I used bx to generate my wallets but only use it for non-BTC coins, do I need to worry?

A: Yes. All funds stored on BIP39 mnemonic secrets or BIP32 wallet seeds are affected since the underlying private keys are basically public now.