In my themes grids and store pages?

Warning: Undefined array key “post” in /var/www/123456/data/mydomain.com/docs/wp-content/plugins/wp-image-sizes/wpis-init.php on line 125

Please update plugin to support PHP8.
You Just need to check that what you are trying to get value is exists or Not So you have to use isset.

No Pro Features needed, just keep it compatible with new versions of WordPress.

Warning: Trying to access array offset on value of type bool in /var/www/123456/data/mydomain.com/docs/wp-content/plugins/wp-image-sizes/includes/wpis-settings.php on line 9
Warning: Trying to access array offset on value of type bool in /var/www/123456/data/mydomain.com/docs/wp-content/plugins/wp-image-sizes/includes/wpis-settings.php on line 10

WP6.0.1

Normal sorting order:
screenshot-1.png

1. Thumbnail
2. Medium
3. Medium_large
4. Large
5. 1536×1536

Abnormal sorting order
screenshot-2.png

1. Thumbnail
2. Medium_large
3. 1536×1536
4. Medium
5. Large

Is there a reason for this?
The brain refuses to quickly switch between different types of representation.
Can you fix it?

What is Create Images on Runtime?
Every time a page is rendered, the necessary thumbnail will be created, right?
Depending on the device, isn’t it?
If the page with specific image size that doesn’t exist loaded on 50 different gadgets with different viewport sizes, will an additional 50 thumbnails be created?