Echoing #27's concern here.
The intentions of this change are fine for "normal links" that contain multiple words.
But maybe no thought was put into 'mailto:' links, where there is typically no natural word breaks in the link's text.
For example: firstname.lastname@longdomainnamehere.com
Our sites had CSS that forced email-address links to wrap if necessary. Extlink's new "extlink-nobreak" markup and CSS overrides that now, and in narrow spaces - like sidebars or cards in a grid-layout - we get a broken layout (horizon overflow, scrollbars) or text that gets cutoff (in cases where the parent container has `overflow: hidden`).
The CSS we were using to ensure long email address links did not break horizontal flow.
a[href^="mailto"] { overflow-wrap: break-word; }
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Our temporary workaround is to completely disable Extlink's processing of 'mailto:' links in the module's options.
We can confirm the original bug report on Drupal 10.2.1 under PHP 8.1.27.
And more importantly, can confirm the crash is fixed after applying a patch for the changes that MR32 makes (https://git.drupalcode.org/project/bootstrap/-/merge_requests/32.patch).