The past participle shown was uncommon before the 19th century, but is now the preferred form in standard English. In the UK, showed is regarded as archaic or dialectal. In the US, it is considered a standard variant form, but shown is more common.

Was shown is correct?

A: The usual past participle of “show” (that is, the form of the verb used with “had” or “have”) is “shown.” But “showed” is also acceptable and not a mistake. ... Although “shown” is the predominant past participle today, according to the Oxford English Dictionary, it only became common in the 19th century.

Have shown up or showed up?

To use "show up" using past perfect, you'd say "she has shown up" just like if you were saying "she has shown" but with "up" added afterwards. You don't use "she has showed".