Seems Youtube may have made a chance to force Shorts on its viewers. I followed instructions before to remove it, seems Google is either no longer allowing that or has some new convoluted new method to opt out.
This seems to be working, will see. Install UBlock first.
Copy the stuff in the gray box in the Shorts section.
On UBlock, click on the gear (settings), go to 'My Filter' tab and paste the filter script copied earlier.