Chapters released after MangaDex.org database problems from last week do not appear in Gallery-DL.

[nexen-eve]

For example:
gallery-dl --chapter-filter "lang == 'en'" --dump-json https://mangadex.org/title/42934
Only detects up to Chapter 13 and not Chapter 14, 15, or 16.
Same results after --clear-cache or with --ignore-config and no chapter filter.

gallery-dl --chapter-filter "lang == 'en'" --write-metadata https://mangadex.org/title/42934
Only downloads up to Chapter 13 and not Chapter 14, 15, or 16.

gallery-dl --verbose --write-metadata https://mangadex.org/chapter/1197680
Trying to manually download Chapter 14 or above results in a 404 Not Found error as seen below.

[gallery-dl][debug] Version 1.16.5-dev
[gallery-dl][debug] Python 3.9.0 - Windows-10-10.0.18362-SP0
[gallery-dl][debug] requests 2.24.0 - urllib3 1.25.10
[gallery-dl][debug] Starting DownloadJob for 'https://mangadex.org/chapter/1197680'
[mangadex][debug] Using MangadexChapterExtractor for 'https://mangadex.org/chapter/1197680'
[urllib3.connectionpool][debug] Starting new HTTPS connection (1): api.mangadex.org:443
[urllib3.connectionpool][debug] https://api.mangadex.org:443 "GET /v2/chapter/1197680 HTTP/1.1" 404 None
[mangadex][error] HttpError: '404 Not Found' for 'https://api.mangadex.org/v2/chapter/1197680'

[nexen-eve]

Might be worth noticing https://mangadex.org/api/v2/chapter/1197680 does contain the chapter data, unlike https://api.mangadex.org/v2/chapter/1197680.

[nexen-eve]

At first glance it seems to be fully functional again when changing api_root in extractor/mangadex.py to https://mangadex.org/api.

[mikf]

The new API server is still having caching issues, it seems.
This was already reported over a week ago (#1290) and they still haven't fixed their servers.

I've changed the default server used by gallery-dl back to https://mangadex.org/api and added an api-server option so this can be adjusted as needed (79c0fc2, ignore the wrong issue number).

Also, according to https://mangadex.org/thread/351011/9/#post_4238014, the API interface on https://mangadex.org/api should have already been disabled.