Update to Drupal 9.3.0 adding --2 suffix to (views-) block-ID's

Problem/Motivation

Updates from Drupal 9.2.10 to Drupal 9.3.0 are adding an --2 suffix to block-ID's (maybe only views-block-ID's?). For example block-views-block-newsslider-block-1 changes to block-views-block-newsslider-block-1--2, causing all JS an CSS selectors applied to the specific IDs not to work anymore and breaking the design of the website. This happens at least to allblock-views-block-Elements of the affected websites.

This happend with different websites and different base themes (Classy, Bootstrap 3).

Setup:

Steps to reproduce

Update from Drupal 9.2.10 to Drupal 9.3.0

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet