Database possibly compromised
Your site contains a skimmer disguised as googletagmanager.eu
. Attackers managed to inject this skimmer in over 270 stores this week, and - sadly - also yours.
In the cases that I investigated, attackers used a flaw in MySQL/adminer to gain access to the victim sites. Because you shared an adminer screenshot, I suspect they used the same method on your store.
You should thoroughly scrutinize your site for hidden backdoors, disguised admin accounts and such. My eCommmerce anti-virus may help. See also:
https://gwillem.gitlab.io/2019/01/17/adminer-4.6.2-file-disclosure-vulnerability/
https://twitter.com/gwillem/status/1098926474571235329