I closed the client after playing and when I am back on the client again in about 3 hours, the client had a bug. First, I noticed the language filter, which I turned off, was turned off. I didn't have client volume on but I could hear the client music. Some of the other settings are changed, for example my league voice changes.
There were also tips and flashing icons about new features added in season 9. There is a pop-out window about season 9 which we've already seen at the start of the season.
After I got into champion selection, I noticed the rune pages that I previously set was gone and instead were the 5 default pages since the season 8 rune reforge. All the changes to the runes recently are marked with a flashing icon.
My summoners' spells are set to smite and heal but I assume it is supposed to be reset back to ghost and heal, I just got the role jungle and it automatically switched to smite for me.
My skins choices are reset back to the original skin. I need to manually set it back to the skin I last played with.
I really hope Riot can resolve the issue since I fear next time I open the client the same bug will happen again. I've seen bug reports about similar bugs happening over and over for one person. It will be extremely frustrating to set your rune pages and settings every time you launch League.
TL;DR Client bug, showed tooltips, custom rune pages are reset. Skin choices and summoners' spells choices are reset in champ select