Scratch Wiki wrote:

When naming a costume as a number, Scratch will be confused if costumes are switched via variable:

switch costume to variable
Especially if the variable is a number.

If possible, costumes should not be named as numbers, as this will eliminate the ability to change to a costume via its number, changing to a different costume instead.

dhuls wrote:

1. According to the Scratch Wiki:

Scratch Wiki wrote:

When naming a costume as a number, Scratch will be confused if costumes are switched via variable:

switch costume to variable
Especially if the variable is a number.

If possible, costumes should not be named as numbers, as this will eliminate the ability to change to a costume via its number, changing to a different costume instead.

2. You can already put variables in the switch costume block, so I'll say this is already implemented.