Perhaps, misunderstanding began with

I think you need to set the precision to 1

which maybe stemmed from

p or precision ... 0 or 1 mean round to integer

which (i.e., Perl core module documentation) is wrong. "0" is "round to integer". "1" is not.

Allowing "accuracy" and "precision" for extended integers (through a pragma i.e. infecting everything which interacts with source code literals!) is, simply, very evil and can lead to bizarre infinite loops, as shown, but it's not a bug in itself, because documented (but should never be used (?))