It is, especially for Medium and Substack posts, websites that my DNS resolver or ISP block, and for webpages that refuse to load with uMatrix in its default setting.
uMatrix in default settings pretty much breaks every website.
You definitely need to whitelist cloudflare CDN and other popular CDNs like Amazon S3, things like jquery.com ,and maybe Google for the recaptcha (unless you whitelist google for individual websites)
For a time, I used https://brow.sh but its hosted html browser is not up anymore.