Possible solution

According to me the word-break class was used to prevent text overlapping in mobile view and on removing this class the desktop view looks fine, as the operation ids are not wrapping now if there is enough space available for them. This class should be added to the media query block instead to prevent overlapping in mobile view.

If this looks fine to you I can raise a pull request for this :)

While it is true that disabling word-break: break-word; fixes the display issue, this is not the reason why the issue occurs now. Swagger UI version 4.15.5 also set this property and it didn't break the operation id display. Some other change between 4.15.5 and 5.17.9 must have caused this.

This was bugging be so I decided to dive into it.

This was introduced in version 5.9.4 with the class opblock-summary-path-description-wrapper, which wraps the path and description to improve the layout on small screens. This has its width set to 100%, so it tries to take up the entire flex container, causing itself and opblock-summary-operation-id to shrink.

This custom css allows the wrapper take up the remaining space in the container without shrinking anything:

.opblock-summary-path-description-wrapper {
  width: unset !important;
  flex-grow: 1;
}

The operation id still breaks if the description wraps, but honestly that's probably fine. I might try and submit a PR if I can't find a better solution.