Steps to reproduce the issue

Disable SEF URLs in the global configuration.
Navigate through the blog articles with the pagination.
It is not possible to get back to first page, the url will always contain the current limitstart= value

Expected result

Navigating back to first page

Actual result

It's not possible to navigate to the first page

System information (as much as possible)

Joomla 3.9.0 stable
Protostar template
Blog demo content

Additional comments

Not sure but maybe caused by this PR #19467

The Router will add the current URL parameters to the created pagination link.