In a recent MediaWiki update the move interface was slightly changed (see T86865: Convert Special:MovePage to OOUI-based form). However, when performing a move with a "wpReason" parameter in the URL, the contents of that parameter are no longer prefilled into the "reason" field. According to PrimeHunter it still works for deletion, though.
The same issue also affects re-submitting the form after errors (or to confirm moving over an existing page) – the contents of the "reason" field disappear and have to be re-typed.
See https://en.wikipedia.org/wiki/Wikipedia:Village_pump_(technical)#File_renaming for a constructed example.