LibreWolf: connect to extensions.allizom.org after Dropbox OAuth

### Which version of floccus are you using?

5.10.2

### How many bookmarks do you have, roughly?

2 (tiny; fresh new setup browser)

### Are you using other means to sync bookmarks in parallel to floccus?

No

### Sync method

Dropbox

### Which browser are you using? In case you are using the phone App, specify the Android or iOS version and device please.

Librewolf 153.0.3-1 (buildID 20260804124254 )
OS: Windows 11

### Which version of Nextcloud Bookmarks are you using? (if relevant)

_No response_

### Which version of Nextcloud? (if relevant)

_No response_

### What kind of WebDAV server are you using? (if relevant)

_No response_

### Describe the Bug

1. install Firefox addon from official firefox/mozilla addons website
2. configure; use "dropbox"
3. Dropbox oAuth - click "Allow"
4. after clicking "Allow" in the Dropbox tab, it auto-opens a new tab: CANNOT CONNECT TO WEBPAGE
https://{...UUID...}.extensions.allizom.org/?code={...}&state={...}

the addon still doesnt receive the auth.
how to fix this in Librewolf?
also can it be reproduced in Firefox (vanilla)?

### Expected Behavior

1. the new tab should NOT:
a) goto an unable to connect page
b) goto ALLIZOM specifically which according to ISUP.ME is DOWN FOR EVERYONE, NOT JUST YOU.
2. the addon should be auth'd for dropbox

### To Reproduce

see above.

### Debug log provided
HELPFUL?
SEE:
https://discourse.mozilla.org/t/oauth2-redirect-to-https-extensions-allizom-org-seems-to-fail/35994/11

- [ ] I have provided a debug log file

Start by reproducing the Dropbox OAuth flow in LibreWolf 153.0.3-1 on Windows 11, then compare it with vanilla Firefox. Inspect the redirect to the reported extensions.allizom.org URL and the linked Mozilla OAuth discussion; done means Dropbox authorization reaches the addon without an unreachable redirect page.

Written by the indexing model from the issue text.