pub const panic = @import("std").debug.no_panic;
var lhs: u3 = 1;
var rhs: u1 = 0;
export fn shlSat() void {
    lhs <<|= rhs;
}

$ zig build-obj repro.zig --verbose-air |& grep cmp_lt
  %4 = cmp_lt(%3, <u1, 3>)

This safety check only applies to <<, not <<|.
As an added bonus for fixing this bug, you can enable the disabled safety checks in test/behavior/bit_shifting.zig and test/behavior/x86_64/binary.zig referencing this issue!