While I personally think that we should just give everything seized from Russia to Ukraine I understand the problem at hand. There needs to be quite a bit of global discussion and agreements on things like this. Global agreemeent to seize whatever you can from a country which invades another one seems like a no brainer, but that blade cuts both ways. With Russia the global effect is pretty minuscle (I think) as most of the global west is already out of there, but if the same situation was with China and Taiwan it's a whole different matter as practically all the western investments in there would just vanish overnight. And should China just decide to stop all exports it would be pretty catastrophic to western wold, military included. And it's pretty much the same picture with USA vs EU, should USA really end up in a dictatorship.

But after that, if EU just decides to seize all Russian assets in order to help Ukraine I would be that it would have pretty much global acceptance behind.