As someone who worked on ad blocking extension, I can tell you Manifest v3 is designed to make this more difficult, limited over time with the intent to pretend "it still work".

Blocklist quotas have been sized to match the current state. With no room to grow. And at the time it still required a complete extension review to update them (not sure this changed)

It's neither security nor performance.

This applies to Microsoft branded version and to Vivaldi. And any other Chromium based browser.