Thanks to the people who worked on this and gave their views and comments, especially, Nicholas K. Dionysopoulos.
These modifications are carried out in order to modernize the updating procedure. Nicholas' changes have eliminated almost half of the code previously utilized, making the process more rational and stable. These improvements will make it easier for future code maintainers.
It will be needed to make adjustments to the htaccess file for anyone using the JDocs toughened version or other htaccess examples to make these changes.
If you do not make these changes, your updates will be banned after Joomla 4.0.4, then it is critical that you take action and make this change.
This does not apply to you if you have never used any of these more complex htaccess files and simply use the core file, however it is worth searching through your htaccess file for the line with:-
RewriteRule ^administrator/components/com_joomlaupdate/restore\.php$ - [L]
And make the required changes if you do come across it in your files:
## Joomla! Update (core feature) — Joomla versions 2.5.1 through 4.0.3
RewriteRule ^administrator\/components\/com_joomlaupdate\/restore\.php$ - [L]
## Joomla! Update (core feature) — Joomla versions 4.0.4 and later
RewriteRule ^administrator\/components\/com_joomlaupdate\/extract\.php$ - [L]
Find more detail here
How to upgrade to Joomla 4?
The first step will be to update your site to Joomla 3.10. The Joomla 3.10 The Pre-update Checker will show you which extensions are compatible with Joomla 4.0 (great, isn’t it?). And then, you just have to follow the tutorial: How to Upgrade Joomla 3 to Joomla 4 Step by Step.
Follow up all of the news of Joomla 4: