France is running on borrowed time economy wise.
Anyway
Summarized version
The West has frozen approximately $300 billion in assets belonging to the Russian central bank. Euroclear, based in Brussels holds around $205 billion.
Euroclear however is a private entity with responsibility (securities trade clearing, management and safekeeping of securities for a large part of the global financial market, overall Euroclear's managed assets are $37 trillion), and thus a huge required capitalization. Once they seize Russian securities, the Russians seize the $33 billion of Euroclear assets frozen in Russia.
And although Euroclear will have to write off $33 billion - repay them to their investors. Or get EU to give them piece of those frozen Russian assets to cover the lose.
Russia can and would sue for seizure of Euroclear's assets internationally - Euroclear has depositaries in Dubai and Hong Kong. And since seizure of sovereign assets is very very much against international law, And likely Russia would win in those countries, So not only would Euroclear take a massive lose. This would threaten Euroclear with loss of license and pretty much put another nail in EU's economy.
And the EU with this move can say goodbye to euro’s status as a reserve currency. and place of investment, etc
Never mind of course destabilizing precedent that western countries would set by doing this. And accelerate the end of the dollar also.