When attempting to load into a previous or new world with multiple add ons that do not conflict with one another player will be met with the block error code and will be redirected to the main menu. The following add ons present in this case are posted below along with the results. All worlds that receive this error worked normally before the 1.21.130 update and the hotfix has not rectified the issue. The amount of add ons needed to recreate this issue varies and therefore cannot be narrowed down to an exact number. This error has happened with 2,3,6, and more add ons.
Your screenshot shows that you are playing in 1.21.130, not 1.21.131. Please update your game to 1.21.131 and see if the issue still occurs. If it does, attach a new screenshot.