Literally what it says: InRelease file from solydxk expected, solydxk-8 (which is Jessie!) received. That's two items you don't need.
Clean up is easy enough. Just go to /etc/apt/sources.list in Thunar and select "Open as administrator" from the context menu so it opens in mousepad. Remove everything and leave just those two lines I mentioned before:
Code: Select all
deb https://repository.solydxk.nl/ solydxk-ee main upstream import
deb http://deb.debian.org/debian/ testing main contrib non-free
If those vivaldi and enpass list files are the only thing in /etc/apt/sources.list.d/ and those files don't contain anything related to solydxk.com, solydxk.nl or debian.org, they shouldn't be an issue.
I just remembered, opening a list file as administrator may open it in the software properties tool instead of mousepad. If that happens, you should open mousepad as administrator first and then load sources.list into it.