No 503 errors. Only a 403 one (top part of screenshot).
I’ve also ss the console. I don’t know if this is relevant to it (bottom part of screenshot). I’ve queried chatGPT about it before, it said it wasn’t relevant but right now, I’m not sure of anything
ChatGPT could not take into consideration of what is happening in InfinityFree, and redirecting error pages to the error.* subdomain is something unique here, although uncommon.
This caused 403 is related because what should have loaded has now became something entirely masked behind another domain, leaving what you have in the console window an irrelevant error hindering your debugging process.
I said if you see, does not mean it has to be, but because of the way errors are shown here, this is unknown.
Whether it’s a 503 or 403 error, the script were still not correctly loaded and you need to check your error logs.
Meanwhile, whether it’s a problem on this hosting specifically or not, only the result matters. You can feel free to use anything that works best for you.
I’m only saying that because you have indicated that you don’t have the issue elsewhere but here.
You can’t be so sure if you don’t know the cause to the problem, but it’s up to you.