I’m a happy user of Sparklin since several years. Today I updated to version 2,4,8 and discovered that the Boostrap tabs stopped working,
Looking into the theme files I have seen that the Bootstrap js has been updated to 4.0.0, but the css is still for Bootstrap 3, which may explain the problem.
What I have tried:
I downloaded the latest Bootstrap 4 (4.6.0) to my child theme, dequeued the sparkling bootstrap js and css and enqueued the Bootstrap 4.6.0 in my child theme, and with that the tabs work again (albeit with some other probems, probably due to other CSS files in my child theme being for Bootstrap 3 and not 4).
Then I did the same thing with Bootstrap 3.4.1, and now everything works, except that I have lost some Sparkling styling that has been overwritten by Bootstrap - but that can be fixed
With the changes in the version of jQuery that comes with Wordpress 5.6, it is clear that the version 3.3.7 of Bootstrap that was previously used in Sparkling had to be updated, but you could have updated to 3.4.1 to avoid complications in child themes, or you could have made it possible to select to use either Bootstrap 3 or 4.
At least you need to provide css-files with the same version of Bootstrap as the js.