Fix regex pattern for ext seq scenario (#3162)

[maddieford]

(cherry picked from commit 23d4c5b)

Description

Issue #

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PR information

• The title of the PR is clear and informative.
• There are a small number of commits, each of which has an informative message. This means that previously merged commits do not appear in the history of the PR. For information on cleaning up the commits in your pull request, see this page.
• If applicable, the PR references the bug/issue that it fixes in the description.
• New Unit tests were added for the changes made

Quality of Code and Contribution Guidelines

• I have read the contribution guidelines.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.62%. Comparing base (a8ac804) to head (6fe114e).
Report is 3 commits behind head on hotfix-2.11.1.9.

Additional details and impacted files

@@               Coverage Diff                @@
##           hotfix-2.11.1.9    #3180   +/-   ##
================================================
  Coverage            71.62%   71.62%           
================================================
  Files                  109      109           
  Lines                16421    16421           
  Branches              2352     2352           
================================================
  Hits                 11762    11762           
  Misses                4112     4112           
  Partials               547      547           

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