Safari downloading html links instead of opening, Keyboard layout getting changed, full screen option not working, MacBook shut down issue, Stage manager not working

I am facing peculiar problem. At times or rather most of the time since last update to macOs 13.4 and 13.5

1. Safari - I am unable to open any webpage. Instead of opening webpages, Safari is downloading html files. Also instead of zoom/minimise icon on top left corner of safari or any other application, i am getting a ‘+’ sign (This happens when safari fails to open webpages). Hovering over same gives me three options such as zoom, tile window to left and right, however after clicking on Zoom, it does not cover entire screen. Also if I have multiple tabs open, and if i close single tab, it is closing all other tabs and keep the tab open (which i want to close)
2. Keyboard - My keyboard layout is getting changed automatically as if i have pressed right 'option' button continuously. I figured that if i OFF sticky keys, it keyboard becomes normal. Luckily I have an external keyboard, using which i am able to enter login password after restart or shutdown, otherwise i would have stuck at Login page forever.
3. Stage Manager - Stage Manager is not working. once i switch ON stage manager, i am unable to see tiles of open windows on left side. If i am moving cursor to left side of monitor, I am able to see only one windows tile even if i have 3 or 4 windows open.
4. Shutdown - If a perform a shutdown option, it restarts instead of shutting down.
5. Logout - I have set logout timer to 1 min of inactivity, however, it does not logout after set time. Also, screen dims after 1 min but becomes full bright after few seconds (which should happen if i touch mousepad or press any keys)