FWIW my break-the-glass actual use of backup codes is for access to my password manager.

Everything else which has ever given me a backup code... gets stored in a secure note in my password manager.

It is just another knowledge-based factor. It is one that they are reasonably sure you aren't spreading around the internet. It is one that the site gets to pick rather than the user. But in reality, they are a often just a way to try to reduce some support and identity verification costs.

The path to get to the password manager is the case where the backup codes truly matter, because without them there may not be a way for support to restore access. Those codes may be your only way of regaining the master encryption key.

But that also winds up being part of the trade-off of security vs user friendliness. Some password managers are way easier to get back into.