[Bug]: Comment entry field disappears when switching tabs in sidebar

[jospoortvliet]

⚠️ 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.

This PR is a fix: #63505

Bug description

The field to enter a comment (in the Activities tab in the sidebar) disappears once you switch tabs and won't come back until you reload the page.

Steps to reproduce

1. open sidebar, go to activity -> see comments and comment field on top.
2. go to versions
3. go back to activity -> no comment field on top, comments and activities still visible.
4. 🪄
5. Reload page brings back the comments.

Expected behavior

Ideally the comment input field doesn't disappear ;-)

Nextcloud Server version

35 (master)

Operating system

No response

PHP engine version

No response

Web server

No response

Database engine version

No response

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

No response

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

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

Configuration report

List of activated Apps

Nextcloud Signing status

Nextcloud Logs

Additional info

using tech-preview with Nc 35 beta, but bug also present on 34.
Browser shows no errors in the console.
Happens both on Safari and Chrome. Andy could reproduce.