From what I gathered from the report, this is especially obtainable on multcoin wallets like Trustwallet, phantom e.t.c. Personally, I always like a bitcoin only wallet and open-source one. Everyday I see more reasons to stick to my Electrum and not try out any other Bitcoin wallet for my major holding because Electrum is lightweight, secured, simple to use and just created for Bitcoin.
I have asked a few of my Bitcoin enthusiastic friends about the best wallet to use and Electrum keeps making a top of the list, it could be to the reasons you have also highlighted and it is point blank a perfect assertion that one's seed phrases is only as secured as the source used to generate it.
No one should use a wallet they don't trust, mostly one that people haven't really heard of like this bloom report has about bx.
This just seconds the opinion that for an investors set up to be strong, they must use a self custody wallet with a strong mathematical link.