No, I wouldn’t consider that to be normal.
Since Output is where InDesign starts dealing with colour conversion, destination profiles, ink handling etc., your colour-profile theory is certainly worth testing.
I’d probably troubleshoot it in this order:
Try a completely new blank document first.
Create a new document, put a simple text frame in it and go to Export > Adobe PDF (Print) > Output.
If it still pauses for 30 seconds, you can pretty much rule out the document itself. If it only happens with certain files, try exporting one of those files to IDML, reopen the IDML and test again. Adobe recommends IDML as one way of eliminating document-level corruption.
Test with one of the standard Adobe PDF presets
Try something like PDF/X-4 rather than one of your own saved PDF presets. If the delay disappears, I’d suspect a damaged/custom PDF preset rather than InDesign generally.
Test the colour profiles
Back them up first, then temporarily move any profiles you have installed yourself out of:
~/Library/ColorSync/Profiles/
and, if you have installed system-wide profiles, check:
/Library/ColorSync/Profiles/
I would not start removing anything from:
`/System/Library/ColorSync/Profiles/`
Those are macOS system profiles.
Restart InDesign after moving the custom profiles and test again. If the Output panel suddenly opens normally, put the profiles back in batches until you find the culprit.
Reset InDesign preferences
Corrupt preferences can cause some fairly odd delays in dialogs and output functions. Adobe specifically recommends resetting preferences when troubleshooting PDF/export and performance problems.
On the Mac you can also use Preferences > General > Reset Preferences On Quit, then restart InDesign.
Obviously make a note/back up anything customised first because this resets more than just the PDF settings.
Try without third-party plug-ins
If you have anything installed that hooks into fonts, colour management, preflight, PDF, DAM systems etc., temporarily disable it and retest. Adobe lists incompatible third-party plug-ins as a possible source of InDesign performance problems.
Turn off Live Preflight temporarily
Window > Output > Preflight and switch Preflight off, then restart InDesign and test. Adobe has documented Live Preflight as a potential factor in PDF-export hangs/performance issues, so it is another easy thing to eliminate.
Try another macOS user account
This is a useful test because it gives InDesign a different user Library, different preferences, caches and user colour profiles. If Output opens immediately under another macOS account, you know the problem is somewhere in your normal user environment rather than the application or hardware.
I’d also be interested to know whether you get the same delay if you go into Print > Output. If both the Print and PDF Export Output panels lag, that would make me even more suspicious of something in the colour-management/profile side of the system.
And because you say it has followed you through several versions of InDesign, that also makes me less inclined to blame a particular InDesign release. Something persistent such as a colour profile, preference migrated between versions, third-party plug-in, PDF preset or user-level macOS configuration would be higher on my list.