Invalid learning since early May

Hello. Since the beginning of May, around May 4-6, the training section has stopped displaying correctly in the old browser version (lichess.org/learn#/). Firefox version 52. Is it possible to solve the problem in the browser without updating the browser?
A sample of how is displayed in the browser: imgur.com/a/AJstqGL

I'm afraid not, sorry. Firefox 52 is no longer supported, only 55+ is.

From the lichess 2 blog:
lichess.org/blog/XMvcJSwAADkA0hPE/lichess-v2-is-here
Firefox 55+ gets full support
Chromium/Chrome 60+ gets full support
Opera 55+ gets reasonable support
Edge 17+ gets reasonable support
Safari 10.1+ gets reasonable support
Internet Explorer is no longer supported
Exotic browsers like Brave are supported if they have a modern rendering engine

No idea why browser versions aren't detected by the site and a message displayed.

@Doofenshmirtz There is a browser warning but it's based on browser feature detection, not version information. Though I don't know why there was no browser warning in this case...

Thanks for the answer!
I will try to find a solution. I work in a regular school and made a touch-screen monitor with chess for pupils in order to instill interest in them. I use your site as an engine (training and puzzles). So that they purposefully or accidentally could not disrupt the monitor, limited access only to learning and puzzles, using a browser of a certain version and plug-ins to it (linux+FF52).

If you are interested in how it worked, here are the screenshots: imgur.com/a/627JhyF

That's nicely done! I hope you find a way to upgrade the underlying browser.

Maybe Pale Moon would work? It's based on Firefox and retains support for certain add-on APIs that Firefox has dropped. Version 28.5 has been reported working with Lichess.

Thanks, all used addons/plugins are configured under FF.