Zen Browser is the Arc replacement I was looking for

Zen Browser has emerged as an ideal replacement for the discontinued Arc browser, offering a similar interface and a strong focus on privacy.

• Atlassian acquired the maker of Arc last year to shift development focus toward its AI-driven browser named Dia.
• Zen Browser replicates Arc's best design elements like a left-hand tab bar and siloed spaces without the intrusive AI features.
• The application operates as a free and open-source project supported by volunteers, prioritizing user data privacy.
• It supports standard Firefox extensions, customizable Zen Mods, and a handy glance view for temporary page previews.
• Current drawbacks include the inability to stream DRM-protected video content from platforms like Netflix and Spotify due to missing Widevine licensing.
• Additional limitations involve partial Web MIDI support and a less structured repository for custom site styling.

Read the original at The Verge