Curiously, I never received any such warning on my Xperia X. Only on my Jolla.
The X updated without a glitch. I am still trying to work out if it made any difference and fixed the browser. I had a rather curious problem introduced in 3.4.0.22 involving playing YouTube videos.

Edit: Aaaannndd... the answer is... NO, it did not. Problem still present.


"What problem?", you may ask.

I use my X (my secondary phone) for primarily just two things. Play an Android game and watch YouTube videos. Most commonly, both simultaneously. Playing YT on the background while playing the game. Which can sometimes take an hour or more in a single go.

After some time of playing YT *and stopping* for whatever reason (by browsing somewhere else, or by putting the phone down for a while), when I return back to YT, it is no longer possible to play any video. I just get the spinner until I close the browser and open it again. Sometimes that does not help and I have to resort to more drastic measures, like flight mode off/on or restart network/Lipstick/phone.

This is new since 3.4.0.22 and was NOT fixed in 3.4.0.24.