What about clicking a checkbox means I'm human? How does Cloudflare determine I'm human from that?
The simplicity of it is logic defying. It used to be that you had to find crosswalks or move puzzle pieces or type blurred letters and numbers, but NOW all the sudden I can just click a box and HEY!, I'm human?
Cloudflare has a bot score. Depending on how sus your bot score is you can use several different levels of verification. The checkbox you refer to is kind of in the middle. There is also a more complicated intrusive captcha and a totally transparent javascript. It’s a pretty slick system.
In the first option, you gain little. Tor already encrypts your traffic, so your ISP can't see inside them. Technically, Tor over a VPN hides the fact that you're using Tor from your ISP, but Tor's snowflake does something similar if you need that.
In the second option, you're revealing your VPN account information, which could theoretically be associated back to you. Tor adds nothing over just a VPN in this case.
A security risk is created, you're creating a permanent guard node by using your VPN with TOR. A lot of people downplay how serious this can be against a dedicated attacker. Sure, it may not matter for most, but for those with the right threat model, it will.