(sqrt(-2))^2

[compsystems]

https://en.wikipedia.org/wiki/Order_of_operations says

The root symbol, √, requires a symbol of grouping around the radicand. The usual symbol of grouping is a bar (called vinculum) ̄ ̄ over the radicand √ ̄ ̄. Other functions use parentheses around () the input to avoid ambiguity.

https://en.wikipedia.org/wiki/Vinculum_(symbol)

sorry google translator ->

on 2-D template of √ included the symbol ̄ ̄ that distinguishes or group the expression of radicand, in 1-D the only way of grouping expression of the radicand is to use Bracket

https://en.wikipedia.org/wiki/Bracket_(mathematics)

√( ), parentheses
√[ ] square brackets
√{ } braces
√<> angle brackets

This is the convention that follow several CAS I've tried
√[-2]^2 == √(-2)^2 == SQRT(-2)^2 = -2 and not SQRT(-2^2)

another symbol to delimit can be ¬

√ ¬

√-2¬^2

I suggest that in Algebraic mode (1-D)
pressing √ key, the parentheses is incorporated on entry line

[√] -> √()