If you want to study you should get advice sooner or later.
For Ukrainian students, the situation around studying looks good, even for those who have already been in Germany. And they have some time to get advice, but they should do it sooner or later.
For the third-country nationals, it is not as good as for Ukrainian students. They should definitely get legal advice soon, especially if they want to fill out an asylum application.
For the Russian students, it looks rather bad with the (further) studies - although those who would have to do military service would have a better chance to get asylum. Asylum applications are quite tricky and tolerations are the worst - therefore this should only be done in an absolute emergency.
Further consultation and help available here