What are potential PhD funding sources for international students in UK? There are several answers available on Academia but all of them are 4 to 5 years old. That is why I am re-asking this question.

I was looking for a PhD in UK and contacted a professor of my interest. He's agree to take me but he said he doesn't have funding.

I searched over internet for potential funding sources but I could not find the one which is completely covering all of the expenses. There is one studentship available but it will only cover fee at home/EU rates, which are much less than international rates. Moreover, I can't apply for commonwealth scholarship.

What are other potential PhD funding sources?

Edit:

The field of study is physical sciences, physics to be exact.
Most universities in the Russell Group provide a scholarship for PhD students in natural and mathematical sciences. Nevertheless, they tend to be very competitive, and, for obvious reasons, there is preference to UK and EU students. Usually, a professor/lecturer writes a project, and if it is approved by the department, a PhD student can be fully funded. It may be the case that your potential supervisor does not want to do this as it is time demanding or the project is not a priority in his/her agenda.
Another way of finding a fully funded PhD studentship is to look for projects that fund an international PhD student. These tend to be less restrictive in terms of your nationality. You can find hundreds of opportunities at:


https://www.findaphd.com/