Given earlier hints of this “blank” response appearing on interactive web pages not rendering (such as, for example, when viewing Archive-dot-org’s front page on TFF and IW-PPC stopped being possible many months back, and Interweb/FF45.9ESR/Nightly 52 on Intel not rendering the front pages of major journalism front pages relying heavily on XHR), it became apparent how the browser engine libraries used for handling/rendering XHR/JS have moved forward to such a level that there are now these graceless drops in render support for older browsers (whose JS-handling lacks means to parse said-latest XHR/JS).
If anything, the gap between A) the falling-off of JS development back-compatibility in current standards; and B) the hitting of hard limits on JS/XHR back-porting (to enable older browser engines to keep up gracefully, if slowly), has C) widened and produced this canyon of unsuccessfully-rendered “current” interactive pages by legacy browsers.
“Graceful degradation” is no longer prioritized on a widest-possible/greatest-common-factor reach so much as it serving a hindrance for advancing current industry standards-based deployment for generating active/interactive pages (including tracking user behaviour within a page and returning that telemetry to the server).
It’s, idk, very disappointing.
[As for Mastodon, I left social media a couple of years ago, including Mastodon instances, so I haven’t tried to, say, log in to my old account on any of my older (or even my newer) browsers in a minute. I do remember being, briefly, on at least one instance, one which used a different code base than Mastodon itself, which seemed to cause more issues on non-current browsers, but I no longer have the login to that instance, much less remember which GNU/Social-based engine they used.]