There is literally no reason to buy a TPM right now.
Even if you are in the very small category of people who doesn't have one, and actually needs any of the "none" new functionality enhancements offered by Microsoft's newest, slower, bulkier, buggier, data-stealingest, less-customizable reskin of vista.
The dumb thing doesn't even have a release date, but its like 6 months away.
Odds are, some opportunistic sociopath decided to spend $1Million buying out every chip they could find, hoping to corner a market which didn't even exist.
If missing a chip means Microsoft reaches the end of intrusively forcing non-optional probably-broken "upgrades" onto your system, then that's probably a good thing.
When was the last time Microsoft added anything to Windows that you actually found useful, or at a minimum could uninstall? I think for me it was the Snip tool, which they are removing for the objectively worse "snip and sketch".
Before that, the improvements were just a laundry list of making the worst parts of windows 8 have a bit more of the functionality of Windows 7; like ditching the unusable "start screen".
So maybe I'm just biased, but so far Windows 11 looks the operating system equivalent of a Samsung Galaxy S21.