You have like 2 options: either you know ALOT about networking to the point you can intercept the VRCA from the VRChat servers before they get encrypted. or you search the interwebs for old archives of avatars, your cache can also work if the specific character has been used prior to the implementation of the encryption.

Okay... From experience with FACS It won't get you banned if you aren't "hotswapping" I myself haven't tried it before, but other than that it should be fine if you're ripping the vrca and extracting it. ALWAYS!!!! be cautious when ripping, uploading, or doing ANYTHING with any type of ripped avatar. Hope this helps! Have a great night or day!