Tony, HNY if I click the square to view the vid full screen I’m not allowed as the browser won’t allow it. I have checked my settings and can’t see any probs.. it’s only PFM which seems to have this behaviour - might it be a setting your end that’s changed?
Just click on the 'YouTube' logo instead. That takes you to it on YouTube and you can go fullscreen there.
I’ve just tried it here and it seems to be working fine for me on my iPad. I’ve changed nothing here.
PS FWIW the way I do this stuff is to be signed-in to YouTube & Google both on my iPad and my Sony Android TV. That way whenever anyone links to anything I want to see I just need to click it for a second or so then it can be found in the history on the TV so I can watch it properly just like a TV program. It really works well. 90% of my TV usage is YouTube these days. I’m currently watching someone build an acoustic guitar.