wp-includes/compat.php:393Converts a string from ISO-8859-1 to UTF-8.
$iso_8859_1_textstringstring function utf8_encode( $iso_8859_1_text ): string { _deprecated_function( __FUNCTION__, '6.9.0', 'mb_convert_encoding' ); return mb_convert_encoding( $iso_8859_1_text, 'UTF-8', 'ISO-8859-1' ); }Introduced in 6.9.0. Unchanged from 6.9.7 through 7.1.0.
Signature, return type and hooks compared across 3 parsed releases.
src/wp-includes/compat.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.