If you can post a link to a live project on repl.it, you may get more help or the problem may vanish; what follows below is my best hunch.
I run mine locally on a node dev server without problem, but I vaguely remember having this problem. I think you have two alternatives. One, add jquery locally and serve it with your other files. That should avoid the cross site problem as it’s on the same site. Two, you could add whatever domain you are getting jquery from to the scriptSrc entry of the content security policy of your helmet configuration (I did this). If it’s allowed, it should avoid the problem.
I have no idea why the problem is intermittent, unless something is caching the jquery file and serving it locally without telling you; I don’t use vscode and I don’t know if it’s that smart.
Or maybe the stock price API is just tired from all the Game Stop quotes it’s having to send.