Can a dying PRAM battery cause display and clock issues?

I purchased an iMac G3 a few days ago (for nostalgia reasons) and all seemed fine with it until last night when I booted it up again and the display was offset to the bottom of the frame, making it cut off. It also had these thin, shaking horizontal lines all the way down the display and when it completed booting up, the date and time was reset to 1902, I believe.

I first attempted resetting the PRAM to no success and then booted the iMac command line prompt to reset the NVRAM and the screen seemed fine in that mode. After it restarted, the screen seemed perfect again for a few minutes until the screen went offset again and the lines return. (The clock did not reset this time)

What could possibly have caused this and how can I fix it?

My theory so far is that it’s a result of the iMac being left unplugged for an extended period of time and has affected the PRAM battery somehow as that would explain the reset on the time and date. Would that also affect the display though?

Picture attached to show the horizontal lines and display alignment.

UPDATE: I left it on for half an hour this morning and the display keeps alternating between working normally and the offset resolution with the shaking lines again. Each switch lasting a couple minutes before going back to the other. Could this still be the PRAM still or would it be more graphics related?