Mozilla lost the Internet because mobile became the most common way to go online, and Mozilla (at least on Android) had been an absolute dumpster fire for years. I tried it a few times, but it would just randomly freeze for a few seconds for no reason. But I could switch to another browser and keep going at the same moment when Firefox froze so it wasn’t a phone issue.
Been a few years since I bothered. But, no never was. It was used on a Nexus S, Nexus 5, Nexus 10, and a Samsung Tab S3. All when they were new devices.
The Tab S3 was the last attempt years ago, but after so many attempts and fails, I just moved on.
And if it had been a low spec device issue, the system would freeze, not the app only.