Sury repository is pushing possibly unwanted upgrades

Hi all,

I am sorry, but I am a bit lost:

Hardware: old pc at home
YNH version: 3.6.5.3
Access: full
Special context / tweaking: none
Apps: ttrss, piwigo, nextcloud, roundcube.

  • I did a routine system update/upgrade, then an app upgrade (the only app upgraded was Nextcloud), then other routine, morning update(s?) / upgrade(s?);
  • Nextcloud complained that php7.0-zip was not installed;
  • I manually "apt install"ed php7.0-zip (which came with dependencies), but the source of the package (blah sury.org blah: WTH?!?) caught my eye;
  • I read some posts about the dependency hell of pixelfed, which is not installed on my instance, but I have not understood everything;
  • 58 packages (yes, fifty-eight) from this Sury repo are now installed on my instance, most of them related to php, but also openssl, libargon, libpcre, libssl, libsodium…

I am a bit worried about this repo mixture in my instance. Is there any way to come back to a pure Stretch/ynh blend? What should I do now, apart from suppressing sury.list?

Thx a lot for everything!