Have they been audited, is it popular? If neither is the case I wouldn't daily drive it. Open-source means transparency but not security. Brave Browser injected promotions into some URLs but even with its open-source nature, it wasn't discovered for a long while because of the huge codebase.
In addition, I don't trust how the site claims "Behind this website, and the related services, is a single computer enthusiast who like to tinker with servers, code and similar things at his free time. There’s thus no corporation behind this website and the only source if income (if any) is based on donations."
That's just asking for vulnerabilities and trouble.