Strange never before seen behaivor in libre calc

Hi, i was working yesterday in excel and those red lines appeared from nowhere and with that tag along with it.
And if i dont’t protect the cells when i’m modifying something in the sheet, for ex, pietre it also got modified in another sheet. And i had “substante aur” from otec sheet apeearing in 3 different sheets.
These red lines appear in all the protected sheets.
What can i do about it and why did it happen? Thanks!

It sounds like an operating system setting. If you were using Windows then I think you might have accidentally turned on Sticky Keys and have CTRL activated when you don’t expect it. When Sticky Keys is activated, pressing a modifier key twice in a row locks the key on.
The effects you saw would be the result of that.
Ctrl+Shift+C turns on Track changes
Ctrl+Click when selecting sheets add sheets to the selection so when you add something to a cell it is added to the same cell in each selected sheet.

In Windows go to Control Panel > Ease of Access Centre > Set up Sticky Keys and disable it if you don’t need it. Untick Turn on sticky keys when SHIFT is pressed five times as well, it could turn it on accidentally. Cheers, Al