Beall's list of predatory journals (https://beallslist.net/) has been an often recommended internet place to check if a journal is predatory. I have two questions about it.
The list provides a good indication of potential predatory journals, but it is by no means 100% accurate and has faced various lawsuits over the years from several publishers.
Ultimately, it is up to the authors to decide if a journal is predatory or not. There are a number of common factors that you can use to decide this for yourself, which I have listed in a paper, viz. “Writing for Publication for Students and University Staff” that is freely available on ResearchGate: https://www.researchgate.net/publication/342549330_Writing_for_Publication_for_Students_and_University_Staff.
I do not know of any specific problems with the list but obviously, there' been a lot of changes since it was last officially published. There has been a lot of additions and some journals/publishers no longer exist.