@tuanphan I have the same issue! Was just testing portrait and landscape orientations and saw it too. Here are my website screenshots from my phone for reference.
@tuanphan hey i tried following but I still end up spacing issues on mobile afterwards. I had to go back in and fix everything to be lined up properly. Its like he said in his tutorial, when you go in to "edit", it snaps everything back in place the way Squarespace has it. Also something i realized is you gave me code to help with my headline to not split the text won't scale to the correct sizing in tablet. Thank you in advance for helping correct Squarespace's oversights 🙏