I think this might be a bug.
when a text area is used in an alert with enough text so that it must auto-expand (auto_expand set to True) there is some not so nice animation that occurs… See minimal example below
My workaround is to set auto_expand to False but not ideal
https://anvil.works/build#clone:JP3CB23RKGSLWCPS=CBOH3EAXTLUHOJ5IFZGRO4XB