This is apparently a translation problem in Bengali and a few other languages. The sprintf() function expects placeholders such as %s instead of <code>%</code> for the "If you pick an option other than Plain" help text (since changeset 45926).
The full error I received in PHP 8.1 is:
Fatal error: Uncaught ValueError: Unknown format specifier "<" in /.../wp-admin/options-permalink.php:38 Stack trace: #0 /.../wp-admin/options-permalink.php(38): sprintf('\xE0\xA6\x86\xE0\xA6\xAA\xE0\xA6\xA8\xE0\xA6\xBF \xE0\xA6...', '<code>%</code>') #1 {main} thrown in /.../wp-admin/options-permalink.php on line 38
Likewise, the "When you assign multiple categories or tags to a post" string needs both the %1$s and %2$s placeholders, though I only had a warning about that in PHP 7.4:
Warning: sprintf(): Too few arguments in \wp-admin\options-permalink.php on line 44