Game not loading with Firefox 75.0 (linux)

Since 2020-04-15 I have been unable to load the game for which I GM in Firefox 75.0. The week before worked fine, though in the mean time I probably updated Firefox. If I try to load a game, I get stuck in the loading screen. I do see the Dynamic Lighting adds, but not much else is changing. The game does load in Google Chrome (though I'd rather not have to use it), so that rules out blocking network requests on OS/network level. Browser: Firefox 75.0 (64-bit) Operating System: Arch Linux Browser Protection: Normally I use no-script and uMatrix, but the same problem occurs with those disabled. Enhanced Tracking Protection is normally enabled, but even with that disabled, the same problem occurs. Console log: Content Security Policy: The page’s settings blocked the loading of a resource at inline (“script-src”). editor:12:1 Content Security Policy: The page’s settings blocked the loading of a resource at inline (“script-src”). editor:13:1 This page uses the non standard property “zoom”. Consider using calc() in the relevant property values, or using “transform” along with “transform-origin: 0 0”. editor Content Security Policy: The page’s settings blocked the loading of a resource at inline (“script-src”). 3 jquery-1.9.1.js:1444:6 Content Security Policy: The page’s settings blocked the loading of a resource at inline (“script-src”). 3 jquery-1.9.1.js:1450:5 JQMIGRATE: Logging is active jquery.migrate.js:20:10 Failed to create WebGL context: WebGL creation failed: * tryNativeGL * Exhausted GL driver options. featuredetect.js:4:111 CAMPAIGN ID: 6383152 instrument.ts:129:35 RTCIceServer.url is deprecated! Use urls instead. 3 app.js:278 70 instrument.ts:129:35 TOUCH SUPPORTED: false instrument.ts:129:35 Failed to create WebGL context: WebGL creation failed: * tryNativeGL * Exhausted GL driver options. app.js:552:30672 TypeError: this.gl is null app.js:552:30713 TypeError: d20.engine.finishCurrentPolygon is not a function app.js:547:12749 TypeError: d20ext.finalPageLoad is not a function startjs:46:105 Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at <a href="https://sentry.roll20staging.net/api/10/store/?sentry_key=fe596f386bb14775b58cad9accd672d0&amp;sentry_version=7" rel="nofollow">https://sentry.roll20staging.net/api/10/store/?sentry_key=fe596f386bb14775b58cad9accd672d0&amp;sentry_version=7</a>. (Reason: CORS header ‘Access-Control-Allow-Origin’ missing). 3 TypeError: d20.textchat is undefined app.js:552:29563 Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at <a href="https://sentry.roll20staging.net/api/10/store/?sentry_key=fe596f386bb14775b58cad9accd672d0&amp;sentry_version=7" rel="nofollow">https://sentry.roll20staging.net/api/10/store/?sentry_key=fe596f386bb14775b58cad9accd672d0&amp;sentry_version=7</a>. (Reason: CORS header ‘Access-Control-Allow-Origin’ missing). I suspect the problem might have to do with some of the last lines: Cross-Origin Request Blocked for sentry.roll20staging.net. Firefox' Network Monitor reports that all requests made to that domain receive a 503 Service Unavailable response. Any ideas what might be causing this problem?

Ah, sorry for being impatient. I did check a number of other similar bug reports, none of which seemed to match what I noticed. However, Yulian K.'s suggestion on changing the sandbox content level in another topic ( <a href="https://app.roll20.net/forum/post/8426341/stuck-on-loading-screen-dot-dot-dot/?pageforid=8508843#post-8508843" rel="nofollow">https://app.roll20.net/forum/post/8426341/stuck-on-loading-screen-dot-dot-dot/?pageforid=8508843#post-8508843</a> ) actually "fixed" my problem. Apparently the WebGL creation failed message is the real problem, not the Cross-Origin Request Blocked message.