use strict;
my $v = 'x';
print qq"$v{a}";
__END__
xa
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use strict;
my $v = 'x';
print qq{$v{a}};
__END__
Global symbol "%v" requires explicit package name at -e line 3.
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Note also that the interpolation code needs to make a decision on where the interpolated scalar ends. For instance, whether "a $b -> {c}" really means:

   "a " . $b . " -> {c}";
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or:

  "a " . $b -> {c};
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Most of the time, the longest possible text that does not include spaces between components and which contains matching braces or brackets. because the outcome may be determined by voting based on heuristic estimators, the result is not strictly predictable. Fortunately, it’s usually correct for ambiguous cases.

I don't see this as a bug. Remember that the right-hand-side of s/// is just a double-quoted string, subject to the usual interpolation rules.

The same disambiguation is needed in regular interpolated strings. Consider this snippet:

use strict;
my $var = "this";
print "$var{whatever}";
__END__
Global symbol "%var" requires explicit package name at -e line 3.
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use strict;
my $var = "this";
print "${var}{whatever}";
__END__
this{whatever}
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I get the same error in both examples:

use strict;
my $v = 'x';
print qq"$v{a}";
__END__
Global symbol "%v" requires explicit package name at rhesa1.pl line 3.
Execution of rhesa1.pl aborted due to compilation errors.
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I agree that the attention should be moved to double quotes, anyway. This gives the very same error as above:

use strict;
my $v = 'x';
print qq{$v\{a\}};
__END__
Global symbol "%v" requires explicit package name at rhesa3.pl line 3.
Execution of rhesa3.pl aborted due to compilation errors.
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while this doesn't:

use strict;
my $v = 'x';
print "$v\{a\}";
__END__
x{a}
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I'm not convinced that it'is an incarnation of the problem described in the documentation, anyway: in our case we have a different behaviour in the very same string when the double-quoted string is delimited with different characters, which is not what's discussed in the docs.

perl -ple'$_=reverse' <<<ti.xittelop@oivalf

Io ho capito... ma tu che hai detto?