deletions in output beginning 1023 characters after record start

[peterwang0]

I am using agrep on a unix system (someone else in our group installed it), and have a strange bug. Using the -d option, a few of the output matching records have deletions that begin after the first 1023 characters (and continue for varying lengths). The behavior is reproducible, given the same input file and command, the exact same output problems occur.
In https://github.com/peterwang0/agrep-test I have put test and output files that demonstrate the problem.
A detailed description is in https://github.com/peterwang0/agrep-test/blob/main/agrep_deletion_bug_github.pdf
Thanks!

[Wikinaut]

In former times I also noticed such a bug, or a similar one, may be caused when the string-in-work is close or crossing a "border" because of chunking.

I remember to have fixed some, but gave up to try to fix later, perhaps the community can help.