Drupal 10.3 changes the sticky implementation, bootstrap sticky functionality.

What a mess. This MR and patch update bootstrap to
a) set the updated class for stick tables (sticky-header),
b) remove the bootstrap custom javascript related to TableHeader, now removed in D10.3, and because of that,
c) require D10.3, dropping D9 support.

In order to make sticky headers work properly, I also had to
a) disable the responsive table option in the theme settings (incompatible with sticky headers) and
b) add custom CSS to set the sticky table's thead to an appropriate background color and change the z-index to 90 (500 is incompatible with other bootstrap z-indices).

This patch worked for me .. Thanks!

It should be noted that since this causes an exception it stops further JS parsing - which when using aggregated JS means that many other JS libraries may not be loaded - so the effect may be far removed from tables.