This kinda makes sense especially for less picky designer regarding their portfolio site colour, typo and overall aesthetics, also embedding prototype is very easy, What are cons though?
The most obvious con to me is the inability or extreme difficulty in changing the URL to something other than
squarespace is not a CMS and not self hosted. There is a self-hosted version of wordpress, but you can just choose wordpress.com instead, if you don't wanna manage your wordpress installation. Doesn't take away from the fact that it is a great idea to use notion for this. But I cannot think of something more unprofessional. As a designer you should care about the way you present your work. Instead you give away control over this to a platform.
I have mine on notion. I always received good feedback. You give your control away as soon as you start using the internet really. So maybe a printed version of your work might even be the right approach if you are worried too much
Just because you don't like it doesn't mean it's unprofessional. There are a plethora of design verticals out there that don't need a flashy website to showcase their process, work, etc. I've seen portfolios made with Notion, Google Sheets, PDFs, and every CMS mentioned here and more. If you can showcase who you are, your work, and your process with a Notion template, why does that mean 'you don't care about the way you present your work' just because you or few people don't like the idea of taking a simpler, 'less-designed' approach as you put it. Design isn't Dribbble...
P.S. SquareSpace absolutely is a CMS...
Great for some. Looks like BootStrap to me.
The design space is comprised of a lot more than graphic designers these days, so I think this is a cool and painless portfolio option for entry-level and mid-level designers for whom graphic design isn't a strength.