As a longtime coder I've found it interesting to dive back into some basic algorithms. Something about how it is taught to students makes it harder than just learning it as an already experienced dev. I find I can gloss over a lot of the stuff, but there are still details that I don't understand.
One thing that helps a lot is modern learning resources, basically websites and videos about the same topics, done by someone else. It's quite different from when I was in uni and you were stuck with the people you had around you and the same old books. Now if I don't quite understand insertion sort, there's a variety of explanations.
For those interested there's a number of UK universities that offer a remote master's. Takes a year full time and two part time, and you can often pay by the module. You might also be able to use the virus situation to get a "non-remote" master's remotely, which my wife managed to do last year.