How do I fix a Squarespace URL redirecting to one of my older URLs?

Question

I recently purchased a new URL. I have a previously owned URL with squarespace, but I have never felt I set it up right. I did all the reading, but it has always felt wrong. But I haven't used that URL yet for more than an alpha test site, so it has never bothered me.

But I built a second site which is now ready for alpha deployment and I bought the URL and I decided to test the page (expecting an error as there is no code there). Instead, it just redirected to my other squarespace URL. I never added or changed a setting.

Thinking I could just send my Github pages through to Netlify and then to squarespace and that might solve it. But it hasn't.

For Netlify I can use https://[site_name].netlify.app/ and this works. It goes to the site I have uploaded from Github.

But if I go to www.[site_name].net (the squarespace is a .net url) I get instantly redirected to https://www.[my_other_url].com/

Also, if I just try the actual squarespace link: https://[site_name].net this also redirects straight to my other url.

I can not work out why this is happening. The squarespace representative I talked to said try switching off your router and on again. Which I did, and this did not work. He said clear your cache. Which I did and this did not work.

He said try with mobile data, which I did... and it did not work. Does anyone have any clue what might be going on?

I have tried clearing the cache. I turned off my router and then turned it back on. I contacted squarespace and they couldn't answer.