I'm a geek as well having built my own computers and worked with the three big operating systems. If Photoshop 7 still works well for you, there's no need to fix it with any newer software. There are a lot of freebies that I wouldn't touch. If a free software is very reputable I'll give it a go and I haven't had trouble with those, particularly open source. A lot of online softwares and services do grab your identity and sell it. I consider Facebook to be a great offender and I got rid of my profile though I suspect that it's still there for always. I will not get on Instagram or Linked In. Suno is a problem for songwriters in that it will take your work and put it in its database for anyone else to use. If you don't mind copyright infringement of your work, well okay. But back to Canva...Serif has been very reputable and they sold to Canva. I still use my Serif software since I paid for it. Canva is based in Australia so they may not have the greed and security holes like Swiss cheese that America has. Naturally, they'll want to include you on more lists and sell more. No matter how careful you are, you'll still wind up on the dark web one way or another. I will lay odds that you're probably all the wiser, Sawmill, than many of us, as you've been in the business of IT.
Cheers! John