This browser has WebGL turned off, so the app cannot start. Compose renders through WebGL and MapLibre draws the map with it, so unlike a normal website there is no reduced version to fall back to.
Privacy-focused browsers often disable it deliberately. In Firefox and its forks you
can set webgl.disabled to false in about:config,
or allow it for this site.
The Android and iOS apps do not need WebGL and work as normal.