I don't think they're talking about email accounts. Bank accounts.
re: encrypted accounts
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My sense is that “encrypted” often refers to communications (such as Proton mail) rather than bank accounts, although any data can be encrypted.
Article below says “encrypted platforms” that “Crooks used on his cellphone”, so I still think it is encrypted email —
<<>> Trump shooter searched for rally site photos, used encrypted platforms, sources say
“briefers [Secret Service and FBI, including Cheatle and Wray] told lawmakers they are still attempting to access three foreign encrypted platforms that Crooks used on his cellphone, multiple sources told CBS News. Sources said officials told lawmakers that the encrypted sites are presenting challenges to investigators and could take time to decrypt.”