It would be good to know what brands/models this applies to. For example, a couple yers ago I was unable to find a specialized data recovery firm that would be able to recover data from a xiaomi device that its owner (a relative who had asked me for help) had forgotten the password to. Supposedly xiaomi phones running miui dont do it in the standard android manner. This is what I was told
edit: phone was running miui eu, bootloader was unlocked