[Bug]: Search: load more results does not work when searching in just one category

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

when searching in just one category, load more does not work

Steps to reproduce

1. search for something
2. click load more in one category, see more results appear
3. go to ... menu, pick that category to just search there
4. click load more
5. see nothing happen

Expected behavior

it loads more results

Installation method

None

Nextcloud Server version

27

Operating system

None

PHP engine version

None

Web server

None

Database engine version

None

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

No response

List of activated Apps

No response

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

this is on cloud.nextcloud.com, 27.2.2 as of this bug report.

Start by reproducing the search flow described: search globally, load more in a category, then select that category and load more again. Trace the category-filtered search path and compare it with the working general path; done means loading more adds results when only one category is selected.