Error: birth date confirmation page not working

[I of the Tiger]

Has anyone else experienced this? The age/birthdate confirmation page seems to be broken for the Mac Steam Client on my MacBook Pro running Mac OS Big Sur 11.6.1 and a fresh install of Stream Client (the Oct 13, 2021 build)

I wanted to look at an age-restricted game, and the screen for confirming age and birthdate popped up.

There are three picklists - day, month, and year. After selecting the day, the month and year picklists don't work - I can scroll the picklist, but it won't let me pick one. I restarted the Steam client and tried again. This time, I tried selecting my birth month FIRST and that worked find, but then it wouldn't let me pick the day or the year. It seems whichever picklist you hit first prevents you from making selections on the other two.

It seems like this is an embedded web page (https://store.steampowered.com/agecheck/app/1734080/) that is not playing well with the Steam Client's browser frame. I posted this to Steam support and they just said all the usual about re-installing the Steam client, restarting my computer, etc., all of which I've done and none of which have helped. Maybe if they get a few dozen more people citing the same thing, they'll pay more attention... Then again, maybe it IS just me... :-p