Ah, mainly I just care that there's a diversity in rendering engines. A) to prevent stagnation, and B) to prevent a monoculture of vulnerabilities. I don't care

Ah, mainly I just care that there's a diversity in rendering engines. A) to prevent stagnation, and B) to prevent a monoculture of vulnerabilities. I don't care that much about which rendering engine a given browser uses all that much. About that particular tab (which I guess you're sending a bug report about), maybe you want to try the same URL in a fresh Firefox profile?