I run it under data folder, here is an output for whole data and appdata_:
$ sudo find data/appdata_ID -type f | wc -l
204388
$ sudo find data/ -type f | wc -l
323014
Here is mysql output with a bit masking:
$ mysql -e 'select * from nextcloud.oc_storages'
+--------------------------------------------------------------+------------+-----------+--------------+
| id | numeric_id | available | last_checked |
+--------------------------------------------------------------+------------+-----------+--------------+
| local::/var/www/nextcloud/data/ | 1 | 1 | | NULL |
| home::USER1 | 2 | 1 | NULL |
| home::USER2 | | 4 | 1 | NULL |
| home::USER | 5 | | 1 | NULL |
| home::USER3 | 6 | 1 | NULL |
| home::USER4 | 8 | 1 | NULL |
| dropbox_external::8xxxxxxxxxxxxxxx// | 10 | 1 | 1537389174 |
| home::USER5 | 11 | 1 | NULL |
| dropbox_external::3xxxxxxxxxxxxxxx// | 15 | 1 | 1538729004 |
| home::USER6 | 16 | 1 | NULL |
| home::USER8 | | 17 | 1 | NULL |
| webdav::USER2@DOMAIN@webdav.magentacloud.de// | 18 | 0 | 1540213359 |
| webdav::USER@DOMAIN@webdav.magentacloud.de// | 19 | 1 | 1564667758 |
| local::/home/USER2/Video/ | 20 | 1 | 1564667757 |
| webdav::USER@DOMAIN@webdav.magentacloud.de// | 21 | 1 | 1564663497 |
| webdav::USER2@webdav.yandex.ru// | 22 | 1 | 1564667757 |
| webdav::USER@webdav.yandex.ru// | 23 | 1 | 1564667757 |
| webdav::USER2@webdav.cloud.mail.ru// | 25 | 0 | 1544089172 |
| webdav::USER2@DOMAIN@USER2@DOMAIN@webdav.cloud.mail.ru// | 27 | 0 | 1544089241 |
| yxyxyxyxyxyxyxyxyxyxyxyxyxyxyxy | 28 | 0 | | 1544089324 |
| webdav::USER2@DOMAIN@webdav.cloud.mail.ru/// | | 29 | 0 | 1544089690 |
| home::USER7 | 30 | 1 | NULL | |
|webdav::USER2@webdav.cloudme.com/USER2/// | 32 | 1| 1564667760 |
| local::/var/www/dokuiki/data/media/USER2/ | 34 | 1 | 1557903654 |
| local::/var/www/dokuiki/data/media/ | 35 | 1 | 1559661957 |
| local::/var/nextcloud/data/ | 36 | 1 | NULL |
| local::/var/www/dokuwiki/data/media/ | 37 | 1 | 1564667759 |
+--------------------------------------------------------------+------------+-----------+--------------+
I can see at least old data and new data folder locations under ID 1 and 36. The /var/www/nextcloud/data/ was old default location and /var/nextcloud/data/is a new one.
The funny thing is that e.g. Dropbox was disabled and deleted from the externals:
sudo -u www-data php /var/www/nextcloud/occ files_external:list
+----------+------------------------------+---------+-----------------------+---------------------+----------------------+------------------+-------------------+
| Mount ID | Mount Point | Storage | Authentication Type | Configuration | Options | Applicable Users | Applicable Groups |
+----------+------------------------------+---------+-----------------------+---------------------+----------------------+------------------+-------------------+
| 8 | /MagentaCloud | WebDAV | Username and password | | enable_sharing: true | USER | |
| 9 | /Externals/MagentaCloud | WebDAV | Username and password | | enable_sharing: true | USER | |
| 10 | /Externals/Local-Videos | Local | None | | enable_sharing: true | USER | |
| 11 | /Externals/Yandex-User1 | WebDAV | Username and password | | enable_sharing: true | USER | |
| 12 | /Externals/Yandex-User2 | WebDAV | Username and password | | enable_sharing: true | USER | |
| 14 | /Externals/CloudMe | WebDAV | Username and password | | enable_sharing: true | USER | |
| 15 | /Externals/DokuWiki | Local | None | | enable_sharing: true | USER | |
+----------+------------------------------+---------+-----------------------+---------------------+----------------------+------------------+-------------------+