Hi everyone!
We've investigated the issue at Opera and found that it was caused by the Opera Wallet extension (v1.17) being incompatible with some WordPress plugins (Gutenberg, more specifically). We've recently addressed this and released Opera Wallet v1.18 to resolve the issue. The extension should be automatically updated once you reopen your browser. If you want to update it manually, go to opera://extensions, turn on Developer Mode, and press Update.
Thank you for your patience, and have a great day!