TRUE and FALSE aren’t possible outcomes of the expression you are trying to evaluation (1=1). That’s why your formula there is failing.
If you put just 1=1 as a formula into a formula field, you’ll get a return value of 1, which is the numeric equivalent of true.
If you put just 1=2 as a formula into a formula field, you’ll get a return value of 0, which is the numeric equivalent of false.
However, Airtable’s SWITCH() function appears to not even be able to evaluate this correctly either:
1 = 1,
Which is odd… but, a SWITCH() statement is really not the best option for a binary/boolean comparison anyhow – it’s a bit overkill, since it’s meant to handle more than just either/or outcomes for an expression.
You can get the outcome you want with a simple IF() statement: