Robin
There have been changed many things, e.g. drivers have been updated, kernels etc, which comes from upstream. Maybe kernel.org or debian has removed something from the kernel, considering the code deprecated, what your specific hardware urgently needs to work? One can only know when inspecting the details.
So, first of all, whenever you ask something like that, volunteer helpers here need to see some details on your machine to enable them giving proper advice. Please run in a terminal window, or after booting to console in case GUI won’t come up:
$ sudo inxi -zv8 --za --zv
And post the output (please format it with the CODE button above the forum entry field for better readability, and note in the command there is a single dash leading the first option, but two dashes leading the others, which is not a typo.)
Additionally you could post the output of
$ sudo dmesg
(Also please format as CODE, for readability)
Depending on the findings, there are some graphics specific boot codes you can try, which possibly allow your Graphics device to work, or you might have to try another kernel version.
Windows is like a submarine. Open a window and serious problems will start.