Third-party Switch 2 docks reportedly no longer compatible after Nintendo's latest console update

Following the latest Switch 2 console update, Nintendo appears to have blocked third-party Switch 2 docks.
Update 21.0.0 was released earlier this week and, finally, adds symbols to indicate if software is physical or digital, among other changes.
However, some Switch 2 owners are reporting their third-party docks no longer work following the update (thanks Kotaku).
YouTuber Austin John Plays tested out some third-party dongles and confirmed, after the update, a video signal was no longer transmitted. Shared on reddit, a number of players shared similar stories.
"Can confirm my 2nd (3rd party) dock in our living room just stopped working as well right after today's update," wrote one reddit user. "A full power cycle did not fix it for me. Quite a bummer as we've been enjoying it issue free for months."
"I finally got around to ordering a dock cable for travel, it arrived today," wrote another user. "Plugged it in, happy it worked right out of the box. Launched a game, update alert, update, cable's borked."
Of course, the console comes with a dock in the box. But some users like to have an extra dock available to play in separate rooms or for travelling. An official dock on the Nintendo store costs £92.99, however, so many users have turned to third-party options.
Eurogamer has contacted Nintendo for clarification on this change.
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